KABUL, Afghanistan (AP) — A suicide bomber sneaked into a police dining hall in central Afghanistan at lunchtime today and blew himself up, killing 12, while a border police officer and a civilian were killed in a separate suicide attack in the south, authorities said.

Investigators are still trying to determine how the suicide bomber passed two checkpoints to enter the crowded hall at about 12:30 p.m., said Uruzgan provincial police spokesman Fared Ayil. He said authorities had not ruled out that the attacker may have been a police officer himself or wearing a police uniform.

The bomber entered the dining hall and detonated a suicide vest just inside the door, he said. The dining hall was on a base in Tarin Kowt, Uruzgan’s capital, used by police assigned to secure the main highway to neighboring Kandahar.