A bomb attack on a teahouse in the ethnically mixed Iraqi city of Kirkuk killed at least 38 people on Friday, July 28, police and medics said, according to Reuters.

The blast tore through the tea shop where people had gathered after breaking their fast for the Muslim holy month of Ramadan in Kirkuk, 250 km north of the capital Baghdad.

The violence is part of a sustained campaign of militant attacks since the start of the year that has prompted warnings of wider conflict in a country where ethnic Kurds, Shi’ite and Sunni Muslims have yet to find a stable power-sharing compromise.

“I left the cafe to go to my shop opposite. When the explosion happened the glass of my shop shattered and I was injured by the fragments. I rushed to the scene... some bodies were dismembered,” said Mohammed, a witness to the blast.

Kirkuk is rich in oil and lies on the front line of a dispute between the Shi’ite-led central government in Baghdad and ethnic Kurds who want the city to be incorporated into their autonomous region in the north of the country.

No one immediately claimed responsibility for the attack, but insurgents have been regaining strength in recent months, recruiting from the country’s Sunni minority, which resents Shi’ite domination since the U.S.-led invasion of 2003.

At least 761 people were killed in militant attacks across Iraq in June, according to the United Nations, still well below the height of sectarian bloodletting in 2006-07, when the monthly death toll sometimes exceeded 3,000.

On Thursday, at least 44 people were killed in bomb and gun attacks across Iraq in the evening.

The death toll later rose to 66, and a car bomb at a Shi’ite mosque in Dujail, 50 km north of Baghdad, overnight brought the number of people killed to 76, police said.