KIEV, Ukraine – The streets of Grozny, the Chechen capital, were the scene of a deadly battle between local security forces and heavily armed militants early on Thursday.

Chechen authorities and local media said militants traveling in several cars gunned down three traffic police at a checkpoint in Grozny before they stormed the centrally located Press House building. A law enforcement source told RIA Novosti that five police officers had died and several have been wounded. Seven militants were also killed.

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A video published online purported to show a shell crashing into the blazing publishing house. Mashable could not verify the footage.

The Moscow-based National Anti-Terrorist Committee said in a statement that security services, police and emergency services personnel had surrounded the Press House building.

After more than six hours of intense fighting, Chechen leader Ramzan Kadyrov said the Press House building occupied by the militants had been destroyed by fire and seven of the militants had been killed.

Later he said several other gunmen had been found in a nearby school and an operation was under way to "liquidate" them, the Interfax news agency quoted him as saying.

The Chechen leader went into more detail in a message posted to his favorite social media platform, Instagram.

“Dear friends! Dogs are dying like a dog! The operation to destroy the bandits is entering its final phase. Six terrorists have been destroyed in the press house! Not one bandit can escape! I am directly supervising the operation. Our main task is to prevent civilian casualties,” Kadyrov wrote in the post, in which he also shared a gruesome photo purported to be one of the militants killed by security forces. At the time he believed six militants had been killed.

In an earlier post, Kadyrov downplayed the situation in central Grozny, saying it was calm and that public services would continue operating, but he urged residents to stay in doors as long as the security operation was underway.

"I ask residents in areas where operations are being carried out to abide by safety measures, and not to go out onto the streets without cause or to go near their windows," he wrote. "All the talk about the city being under the control of military is absolutely false."

Russia’s Life News, which is closely tied to Russian security services, cited law enforcement officials as saying some 15 militants hijacked three taxis late Wednesday in the village of Shalazhi and drove them to Grozny, about 30 miles away.

In response, the National Anti-Terrorist Committee said in its statement that a counterterrorism regime had been imposed on central Grozny, allowing for increased security measures to be enacted.

It posted a photo to its website that showed armored vehicles moving through residential streets of the Chechen capital. The image was widely shared on Twitter.

An Associated Press reporter saw the Press House building engulfed in flames early Thursday and heard the sound of heavy-caliber gunfire before dawn, several hours after the battle broke out.

That AP reporter also reported seeing the body of an apparent civilian in the street near the Press House as fighting raged on, but it was unclear how and when the person had been killed.

Kadyrov said that no civilians had died during the battle.

Another unconfirmed video shows the press house building burning and bullets whizzing through the air. The sound of automatic gunfire is punctuated by the boom of artillery.

The motive behind the attack on Thursday was unclear. But the Kavkaz Center website linked to a video message by a man claiming responsibility for the attack. The site is used by Islamic militant groups operating in Russia's North Caucasus.

The man in the video said he was operating under orders from Chechen Islamist leader Aslan Byutukayev, also known as Emir Khamzat.

Mashable could not verify the video.

Unrest is not uncommon in Russia's North Caucasus, where Chechen leader Ramzan Kadyrov has cracked down hard on militant groups since 2005. In October, a suicide attack in the Chechen capital killed five policemen and wounded 12 others.

Kadyrov has been widely criticized by the international community for human rights abuses. He has also been accused of eliminating his adversaries.

Thursday’s attack shattered a period of relative calm in the north Caucasus and sparked concerns of a fresh outbreak of violence in the region, where Russia has fought two bloody wars with Chechen separatists since the collapse of the Soviet Union in 1991.

Human rights organizations estimate that between 30,000 and 40,000 civilians were killed during years of fighting in Chechnya.

Putin, who was set to deliver his annual state of the union address on Thursday, has long promised to crush insurgents in the Caucasus. He reportedly rushed to the Kremlin around 1 a.m. local time on Thursday and convened an emergency meeting with security officials as news broke of the Grozny attack.