UPDATED: 5 p.m.

One worker was injured trying to extinguish a fire on a high-rise in Southwest Portland on Sunday.

The blaze ignited on the roof of the building at Southwest 10th Avenue and Alder Street, firefighters said in a release.

Workers unintentionally started the fire Sunday morning, investigators found. Roofers were using a propane torch to dry the roof deck so they could apply a primer when the torch flames ignited primer that had already been applied. The fire spread to a large stack of highly flammable foam insulation. The workers used six fire extinguishers but failed to put out the fire before the fire crews arrived.

When firefighters arrived, they found smoke and flames shooting from the roof. Nearly 30 units were called to the scene because of the height of the building.

Contractors alerted 911 to the fire. The building is vacant and under renovation. The injured worker suffered second degree burns but was treated and released at the scene.

The fire was extinguished before 10 a.m. but streets remained blocked for several hours Sunday.

The Portland Streetcar service has been restored.

"When working with an open flame, it is important to keep flammable materials a safe distance away," Portland Fire & Rescue officials wrote in a press release. They urged people to keep a steady water nearby in case of emergencies.

-- Lynne Terry