LOS ANGELES - A raging fire Monday destroyed a massive apartment complex under construction in downtown Los Angeles, sending up flames that were visible for miles while raining ash on a large area and snarling rush-hour traffic.

It was one of two destructive early morning fires in the city. The other heavily damaged a building that houses multiple businesses in a neighborhood a couple miles away.

More than 250 firefighters fought the downtown blaze that was sparked around 1:20 a.m. local time at a block-long building site, Los Angeles Fire Department Chief Ralph Terrazas said.

Flames consumed the seven-story, wood-framed structure and scorched adjacent high-rises before being brought under control within 90 minutes.

The radiant heat was strong enough to burst or crack windows in three nearby buildings that house city and county offices, including the L.A. Department of Water and Power.

Three floors of one adjacent building were damaged by fire, and 14 other floors sustained water damage.

Embers spewed from the fire landed across a freeway, igniting brush and charring a traffic sign. But fortunately, winds were light and did not blow the fire even farther.

Portions of U.S. Route 101 and Interstate 110 were shut down for a time as burning debris fell into lanes. Commuter traffic - slow-moving on good days - remained jammed long after rush hour, with vehicles backed up for miles even after the freeways reopened.

No injuries were reported. The burned structure was planned to be a 1.3 million-square-foot residential building - one of a series of very large complexes that have gone up in recent years.

Shortly after 4 a.m., another large fire was reported at a mixed-use building undergoing renovations about two miles to the west. More than 100 firefighters from multiple agencies responded and had the flames under control in less than two hours, according to Chief Deputy Mario D. Rueda.