Suicide bombers attacked a state-run power station north of Baghdad early on Saturday, killing seven people and forcing the site to shut down, police and army officials said.

At least three gunmen wearing explosive vests attacked the station near the northern city of Samarra. They used grenades to enter the site.

“I was in my night shift and suddenly heard shooting and blasts,” said Raied Khalid, a worker who was wounded by shrapnel. “A few minutes later I saw one attacker wearing a military uniform and throwing grenades through the windows.”

The attackers briefly took over the station, security officials said, but the police regained control after three hours.