Anchorage firefighters doused a fire on the playground at Mountain View Elementary School Tuesday night.

The first sirens screamed through the neighborhood just after 7 p.m. as a thick column of black smoke billowed above the school and a crowd gathered on the sidewalk out front. Kids on bikes circled in the street; teens and elders recorded the scene on iPhones.

Police cars and fire engines blocked the intersection of North Bragaw Street and McPhee Avenue, and traffic backed up on the streets around the school. The black smoke turned white as firefighters brought the blaze under control. Around 7:20 p.m., a police officer asked onlookers to move from the sidewalk so firefighters could access a fire hydrant in front of the school. The smoke was beginning to clear and the crowd was, too.

A rumor that the fire was intentionally set spread up and down the street Tuesday night; the cause of the fire was undetermined as of Wednesday morning, according to Anchorage Fire Department Assistant Chief Erich Scheunemann. The Anchorage School District says the fire caused nearly $100,000 in damage, according to a report by KTVA CBS 11 News.

Update: Investigators identified two juvenile boys as the suspects responsible for the July 10 playground fire, and the case was subsequently forwarded to the Department of Juvenile Justice, the Anchorage Police Department announced July 18.