A series of bombings killed at least 27 people across Baghdad on Saturday, shaking the fragile sense of security the capital has maintained despite Islamist armed group’s offensive raging across northern and western Iraq.

The attacks are among the most significant in Baghdad since armed fighters led by the Islamic State group captured Mosul, Iraq's second-largest city, last month at the start of its blitz. After Mosul's fall, the government moved aggressively to try to secure Baghdad amid fears it might fall as well, and the city has seen few major attacks in recent weeks.

Saturday's deadliest bombing took place in the Shia neighborhood of Abu Dashir, where a suicide attacker rammed a car packed with explosives into a checkpoint, killing at least nine people and wounding 19, officials said. Four policemen were among the dead, a police officer said.

Later in the day, three car bombs in different neighborhoods of Baghdad went off in less than 10 minutes, hitting the districts of Baiyaa, Jihad and Khazimiyah. The attacks killed at least 15 people and wounded another 42, police officials said.

Another car bomb near a bus stop in Khazimiyah killed three people and wounded 15, police said.

Hospital officials in Baghdad confirmed the casualty figures in all of the attacks.

The officials spoke on condition of anonymity because they were not authorized to brief journalists.

The blitz, led by the Islamic State, has pushed into areas west of Baghdad and also has established a presence in a belt of Sunni areas running south and north of the capital. Baghdad itself has a predominantly Shia population.

Iraq's Shia clergy as well as Western powers have pressed politicians to overcome their deadlock and agree to a new unity government to help tackle the insurgency and prevent Iraq from splitting down ethnic and sectarian lines.

The Iraqi military launched a counteroffensive late last month to try to dislodge insurgents from the city of Tikrit, some 80 miles north of Baghdad. That effort has sputtered but has managed to secure much of the highway between Tikrit and the city of Samarra, home to one of the most important Shia shrines. Tikrit itself remains controlled by the Islamist fighters.

Northwest of the city, heavy fighting has raged around an air base that previously served as a U.S. military facility known as Camp Speicher.

On Saturday, Iraqi military spokesman Lt. Gen. Qassim al-Moussawi denied reports that Islamic State fighters had captured Camp Speicher, saying government troops repelled an attack the day before and the base remains firmly in government hands.

Three security officials confirmed the fighters launched an assault on the airfield late Thursday, blasting through an outside wall of the base and destroying one helicopter. One of the officials said the other helicopters at Speicher were "evacuated" from the base to prevent them from being damaged, but they have since been returned to duty.

The officials spoke on condition of anonymity because they were not authorized to brief the media.

A resident of Tikrit, Ahmed Jassim, said by telephone that clashes were taking place around Speicher on Saturday, but "the gunmen are outside the camp." The center of Tikrit is still under insurgent control and is being shelled by the Iraqi military, he said.

Wire services