Islamic State militants are claiming responsibility for a triple suicide bombing that killed at least 58 people in Iraq Sunday, as activists say Kurdish fighters have been able to halt the advance of the extremist group in the Syrian border town of Kobani.

The Britain-based Syrian Observatory for Human Rights told the Associated Press the Islamic State militants, also known as ISIS or ISIL, have not been able to advance in Kobani since Friday but are sending in reinforcements. The Observatory's chief, Rami Abdurrahman, said the group appears to have a shortage of fighters and has brought in members of its religious police known as the Hisbah to take part in the battles.

Sources told Fox News that an intensified wave of airstrikes by a U.S.-led coalition in Kobani may be finally having an effect in the fight. The militants appeared to be slowing down in their intensity and the rate of attacks.

A source close to the Kurdish fighters also told Fox News that the militants have not advanced in the town since Friday. He added that the airstrikes have become "more serious" in the last five to six days.

The coalition, which is targeting the militants in and around Kobani, conducted at least two airstrikes Sunday on the town, according to an Associated Press journalist. The U.S. Central Command said warplanes from the United States, Saudi Arabia and the United Arab Emirates conducted four airstrikes in Syria on Saturday and Sunday, including three in Kobani that destroyed an Islamic State fighting position and staging area.

The Syrian Kurdish enclave has been the scene of heavy fighting since late last Month, with the heavily armed Islamic State fighters determined to capture the border post and deal a symbolic blow to the coalition air campaign.

In Iraq, the triple attack dealt major blows to Iraqi security forces struggling to combat the Islamic State extremist group. It took place in Qara Tappah in the ethnically mixed Diyala province.

An official from the Kurdish Asayish security forces told the Associated Press that the first bomber detonated an explosives vest at the gateway to a security compound that also houses the office of a main Kurdish political party. Minutes later, two suicide bombers plowed cars filled with explosives into the compound, causing heavy damage, he said.

The Islamic State extremist group claimed the attack, saying it was carried out by three foreign jihadists. The authenticity of the online statement could not be independently verified, but it was posted on a Twitter account frequently used by the militant group.

Hospital officials confirmed the casualties in Sunday's bombing in Iraq. Bashir al-Dalawi, a member of the Qara Tappah municipal council, where the attacks took place, said that the bombs detonated near a government building, leading to the higher death toll. He says at least 107 people were wounded in the attack.

He added that some of the wounded were sent to hospital in the Kurdish self-ruled region for treatment.

Also on Sunday, a roadside bomb killed the police chief of the western Anbar province. Brig. Gen. Ahmed al-Dulaimi was killed while traveling in a convoy north of the provincial capital Ramadi through an area cleared by Iraqi security forces a day earlier, Anbar councilman Faleh al-Issawi said. It was not immediately clear if others were killed or wounded.

The extremist group has carved out a vast stretch of territory stretching hundreds of miles from northern Syria to the outskirts of Baghdad and imposed a harsh version of Islamic rule. The fighters have massacred hundreds of captured Iraqi and Syrian soldiers, terrorized religious minorities, and beheaded two American journalists and two British aid workers.

The attack in Anbar followed a bloody day in the capital, Baghdad, where a series of car bomb attacks killed at least 45 people in Shiite-majority areas. The Islamic State group also claimed responsibility for those attacks.

The U.S. military said Saturday it launched airstrikes north and west of Baghdad, hitting a small Islamic State fighting unit and destroying armed vehicles. It said Britain participated in the airstrikes.

Fox News' Greg Palkot and The Associated Press contributed to this report.