Irbil, Iraq(CNN) Iraqi forces are approaching a key area in western Mosul housing government buildings as they push beyond the city's airport and a nearby military camp, Iraqi officials said Friday.

They're in the second phase of a months-long operation to clear ISIS militants from the key Iraqi city.

Taking western Mosul from ISIS: 5 key questions

"Our forces are only 1 kilometer from al-Dawasa neighborhood," Lt. Gen. Raid Shakir Jaudat of the Iraqi Federal Police told CNN.

The area is home to the city's police directorate, courthouse, main military hospital, Turkish Consulate and the Mosul Museum.

Mosul International Airport and the nearby Ghazlani military camp on the outskirts of southwestern Mosul have been fully liberated, the Iraqi Joint Operations Command said Friday.

More than 50 ISIS militants were killed and scores wounded in Friday's operation Friday, Jaudat said. Iraqi forces also destroyed 25 improvised explosive devices and seized several weapons as they liberated the first residential neighborhood in western Mosul, he said.

Iraqi Prime Minister Haider al-Abadi congratulated the armed forces on their victories against "defeated Daesh terrorist gangs," using an Arabic name for ISIS.

"We will exert the utmost effort to rescue the civilians and protect them, provide safe corridors for their exit, receive and (transfer) them to the safe camps." Abadi said in a statement from his media office.

The International Rescue Committee warned this part of the operation could be the "most dangerous phase" for civilians as Iraqi troops seek to secure densely populated areas amid ISIS resistance.

"This will be a terrifying moment for the 750,000 people still in the west of the city, and there is a real danger that the battle will be raging around them for weeks and possibly months to come," said Jason Kajer, the Iraq acting country director for the humanitarian group.

"Everything must be done to keep civilians out of the firing line, and as Iraqi forces reach individual neighborhoods, people must be given the opportunity to escape the city safely."

ISIS militants use tunnels to escape

On Sunday, Iraqi forces launched a new bid to retake the western parts of the city after declaring the east had been liberated last month.

The east and west is divided by the Tigris River, and US-led coalition airstrikes have damaged all five bridges connecting the two sides in an effort to contain the militants in the west.

A CNN crew near the airport reported an intense bombardment Friday on ISIS targets in the southern suburbs.

All day, attack helicopters have been firing missiles and heavy machine guns into the city, the crew said. A group of American spotters was providing targeting information to the helicopters. Iraqi troops could also be seen heading toward the front line.

Mosul: Iraqi-led forces push into key city Members of the Iraqi federal police wave the country's flag as they celebrate in the Old City of Mosul on July 9, 2017. Iraq declared victory against ISIS forces in Mosul after a grueling monthslong campaign. The battle to reclaim Mosul, the last major ISIS stronghold in Iraq, has been underway since fall 2016. This injured girl was found by Iraqi forces as they advanced against ISIS militants in the Old City of Mosul on Monday, July 3. She was carried away for medical assistance. A suspected ISIS fighter is held in a basement while Iraqi forces continue to push for control of the Old City of Mosul on Monday, July 3. An Iraqi Special Forces soldier exchanges fire with ISIS militants in the Old City on Friday, June 30. A bomb explodes near the al-Nuri mosque complex on Thursday, June 29. Iraq's military has seized the remains of the Great Mosque of al-Nuri. Iraq and the United States have accused ISIS of blowing up the historic mosque. Members of the Iraqi Federal Police hold a position as US-led coalition forces advance through the Old City on Wednesday, June 28. The remnants of Mosul's ancient leaning minaret are seen in the Old City on Sunday, June 25. ISIS' claim that US warplanes were responsible for the destruction of the minaret is "1,000% false," US officials told CNN. Two boys comfort each other after their home collapsed during fighting between Iraqi forces and militants in Mosul on Saturday, June 24. The boys, who are cousins, said some of their relatives were still under the rubble. An Iraqi soldier helps transport a girl as residents flee their homes west of Mosul on Friday, May 26. Displaced Iraqis make their way through rubble after evacuating their homes in a neighborhood of west Mosul on Wednesday, May 17. An Iraqi man tries to extinguish a burning car during fighting in Mosul's western Rifai neighborhood on Tuesday, May 16. A member of the Iraqi counterterrorism service secures a building as troops push toward Mosul's Al-Oraibi western district on Sunday, May 14. A smoke cloud rises on the front line as the Iraqi Emergency Response Division advances in west Mosul on Saturday, May 6. A wounded man is transported in western Mosul on Friday, April 21. An Iraqi federal policeman smokes during a break from battle on Wednesday, April 12. A member of Iraq's security forces stands guard in eastern Mosul as smoke rises from the ISIS-controlled western section of the city on Friday, April 7. Iraqis visit a bath house on the southern outskirts of Mosul on Wednesday, April 5. Flames billow from an explosion in Mosul during a clash between Iraqi forces and ISIS fighters on Sunday, March 5. Families are forced to evacuate as Iraqi forces advance in western Mosul on Thursday, March 2. The number of internally displaced people has surged as the offensive effort has intensified. Mosul residents cross a damaged bridge in the al-Sukkar neighborhood on Saturday, January 21. French President Francois Hollande and French Defense Minister Jean-Yves Le Drian, right, view territory held by ISIS during a visit to a military outpost near Mosul on Monday, January 2. A young girl takes part in a Christmas Day Mass at a church in the predominantly Christian town of Qaraqosh. The area's churches were heavily damaged by ISIS militants before the town was freed by Iraqi forces during the Mosul offensive. Iraqi Shiite fighters ride through a desert area near the village of Al-Boutha al-Sharqiyah, west of Mosul, on Friday, December 2. Internally displaced Iraqis who fled the fighting in Mosul watch as a civilian drone films them at the al-Khazir camp on Thursday, December 1. An Iraqi soldier searches a home for ISIS militants after Iraqi forces retook the village of Al-Qasr on Wednesday, November 30. Iraqi soldiers transport a comrade who was injured during a battle near the village of Haj Ali on Tuesday, November 29. A man mourns during the funeral of four Iraqi paramilitary fighters who were killed in battles in the town of Tal Afar. Displaced civilians return to the village of Tall Abtah on Friday, November 25, after Iraqi forces retook the village from ISIS. Iraqi civilians sit on the ground in Mosul on November 24. An Iraqi officer addressed the group, demanding to know the whereabouts of alleged ISIS militants who opened fire on troops a few days earlier. An injured baby receives treatment at a field hospital in Mosul on November 15. A woman cries Sunday, November 13, after seeing the St. Addai church that was damaged by ISIS fighters during their occupation of the Keramlis village. An Iraqi special forces soldier prays next to a Humvee before troops pushed toward Mosul's Karkukli neighborhood on November 13. A Kurdish Peshmerga fighter holds part of a defused bomb planted by ISIS militants in Bashiqa, Iraq, on Friday, November 11. A member of Iraq's special forces guards two suspected ISIS fighters found hiding in a house in Mosul on November 11. An Iraqi woman displaced by war holds her cat near a checkpoint in the Iraqi village of Shaqouli, east of Mosul, on November 10. Iraqi troops watch a broadcast of Donald Trump's acceptance speech in a house in Arbid, on the outskirts of Mosul, on Wednesday, November 9. Iraqi Prime Minister Haider al-Abadi congratulated Trump on his win and said he hoped for continued support in the war on ISIS. US Marines install equipment at a coalition base in Qayyara on November 9. An Iraqi forces member investigates a mass grave that was discovered after coalition forces recaptured the area of Hamam al-Alil on Monday, November 7. Iraqi children witness a man being interrogated by a member of the Iraqi army at a base next to the Al-Intissar neighborhood of Mosul on November 7. A civilian man who fled the fighting trims his beard after reaching an Iraqi army position in Mosul on November 7. Children play in debris created by an airstrike in Qayyara on Sunday, November 6. Female members of the Freedom Party of Kurdistan sing as they hold a position near Bashiqa on November 6. A baby is passed through a fence back to his mother at a refugee camp in the Khazir region on Saturday, November 5. People line up to receive food at a refugee camp in the Khazir region on November 5. Thousands are taking refuge in camps set up for internally displaced people. Iraqi soldiers pass near a bridge destroyed in an airstrike in Qayyara on November 5. Iraqi soldiers patrol an alley on the outskirts of Mosul on Friday, November 4. A suspected member of ISIS is detained at a checkpoint near Bartella, Iraq, on November 4. Iraqi families pack into a truck to be moved to camps on Thursday, November 3. An Iraqi special forces soldier searches for the location of an ISIS sniper in Gogjali on November 1. A man fleeing the village of Bazwaya carries a white flag as he arrives at a checkpoint on November 1. An Iraqi soldier receives treatment after being injured during clashes with ISIS fighters near Bazwaya on October 31. An Iraqi soldier navigates through a shattered windshield as coalition forces advance on Bazwaya on October 31. Archbishop Yohanna Petros Mouche, center, performs Mass in the liberated town of Qaraqosh on Sunday, October 30. Children play in a camp for internally displaced people near Kirkuk, Iraq, on October 30. More than 600 families from Tel Afar, a town west of Mosul, have been living in the camp since ISIS took control of the area in 2014. Displaced families are seen on the road near Qayyara on Saturday, October 29. U.S. military personnel take cover in a bunker after a mortar alarm was sounded at a coalition air base in Qayyara on Friday, October 28. Women and children grieve over the grave of a family member at a Qayyara cemetery damaged by ISIS on October 27. Residents of Qayyara wait for distribution of food and water rations on October 26. Local water sources have been contaminated by the burning oil and sulfur. Iraq's counterterrorism forces advance toward ISIS positions in Tob Zawa on October 25. Soldiers give first aid to an injured boy in Tob Zawa on October 25. Kurdish Peshmerga forces take positions as they start to move toward the Imam Reza and Tizxirab villages of the Bashiqa district on Sunday, October 23. Iraqi forces distribute fruit in the village of al-Khuwayn, south of Mosul, after recapturing it from ISIS on October 23. Kurdish security forces detain a suspected member of ISIS in the eastern suburbs of Kirkuk on Saturday, October 22. An Iraqi forces member helps a man push a car as they arrive at a refugee camp in Qayyara on October 22. Spent bullet cartridges litter the street around the Jihad Hotel, where ISIS militants battled Iraqi security forces in Kirkuk on Friday, October 21. Gen. Abdel Ghani al-Asadi, who leads Iraq's counterterrorism forces, sits in Bartella on October 21 after the town was reclaimed. Peshmerga fighters look over a village during an assault near Bashiqa on Thursday, October 20. Iraqi forces head toward the front lines near Qayyara on Tuesday, October 18. A Peshmerga fighter peers up from an underground tunnel in the liberated town of Badana on October 18. ISIS fighters have built tunnels below residential streets to escape from airstrikes. Kurdish security forces take up a position near ISIS-controlled villages on Monday, October 17. Smoke rises from a suicide car bomb attack carried out by ISIS in the village of Bedene on October 17. Members of the Iraqi coalition gather around a fire at Zardak mountain ahead of the offensive. Peshmerga forces deploy in the dark near the village of Wardak early on October 17.

The firepower seems more intense than when Iraqi forces moved into eastern Mosul last year, the crew said.

Iraqi flags are now flying atop the buildings of the strategic Ghazlani military base near the airport, Col. Mohamad Bayzani said, quoting a statement issued on behalf of the Iraqi forces commander in Nineveh, Gen. Abdul Amir Rasheed Yarallah.

Militants used tunnels to "escape" from western Mosul when Iraqi security forces stormed the camp Friday, an Iraqi special forces officer told CNN.

Iraqi jets target ISIS

On Friday morning, Iraqi F16 fighter jets also conducted strikes on ISIS targets in both Syria and Iraq for the first time.

The strikes were carried out on the order of the Iraqi Prime Minister, according to statements from his office and the Joint Operation Command. They were in response to this month's devastating car bomb attacks in Baghdad's al-Bayaa and al-Habibiya neighborhoods that killed scores of people.

The airstrikes destroyed ISIS bases in the Syrian border town of Abu Kamal and Husaiba in Iraq's western Anbar province, the statements said.

Top general: US mulling 'long-term' commitment in Iraq

Full control of Mosul airport

Iraqi forces secured the airport in Mosul overnight Thursday. The airport was largely destroyed by ISIS forces since its seizure in 2014.

Brett McGurk, the US envoy for the anti-ISIS coalition, congratulated Iraq on its victory.

"Congratulations to Iraqi forces for completing complex maneuver ops to secure #Mosul airport from #ISIS terrorists," he tweeted. "#ISIS is now trapped."

British Major Gen. Rupert Jones, deputy commander of Operation Inherent Resolve, offered a more muted assessment of the situation on the ground, telling CNN's Christiane Amanpour the airport looks "reasonably well-secured."

"It's been a really good day," said Jones, speaking Thursday from Baghdad. "The Iraqis are on the airfield."

A CNN crew saw piles of rubble littering the runway, which ISIS placed there to prevent anyone using the airport.

Iraqi Federal Police and rapid response forces, backed by drones and heavy artillery, advanced from several positions to storm the airport, Jaudat said in a statement.

Forces took the airport in a few hours. But the push to retake western Mosul is expected to take some time -- it took more than three months to wrest the city's east from ISIS' control.

The offensive to take Mosul back began in October in an extraordinary union of Iraqi troops and militia representing minority ethnic and religious groups that have often stood on opposing sides in Iraq's history.