BUJUMBURA, Burundi - In coordinated attacks, gunmen stormed three military installations in Burundi before dawn Friday. At least 15 people were killed as gunfire and explosions rocked the capital, marking a steep escalation of a simmering conflict.

Around 4 a.m. local time, the unidentified attackers wearing civilian clothing hit two military installations in the capital and one in the countryside, showing a level of military sophistication. Terrified civilians in Bujumbura, the capital, stayed in their homes as stray rounds hit some of them.

The sounds of battle continued into the afternoon Friday with military and police vehicles the only ones on the deserted streets. Roadblocks were set up in part of the city, residents said.

"A stray bullet hit the wall of my neighbor's house. We do not know what's going on in the streets. We are living in fear," said Claire Biguda, a resident of Nyakabiga neighborhood, who was locked up in her house along with her husband and two children.

Taxi driver Emery Sahabo said that amid roadblocks and gunfire early Friday, he and other motorists abandoned their cars and ran home.

The International Committee of the Red Cross tweeted: "We are unfortunately unable to move around town for now, hoping to be allowed to provide assistance quickly."

Burundian officials have previously accused neighboring Rwanda of supporting an insurgency against President Pierre Nkurunziza. It was unclear whether these were the attackers. There was no immediate comment from Rwanda.