Expanded coverage of the fire| Lee McGuire's 11 News report

Firefighters rescued some construction workers trapped on the roof, according to HFD District Chief Tommy Dowdy.

There were no reports of injuries, but the sight of thick black smoke hovering over the Medical Center was unnerving, to say the least.

From Air 11, Construction equipment could be seen in flames on the roof of the building. Smoke was also pouring out of the fourth and fifth floors, according to 11 News reporter Lee McGuire.

The M.D. Anderson sky bridge, Rotary House and faculty center were evacuated as a precaution.

Floor sweeps were conducted in those buildings to make sure everyone made it out safely.

KHOU - TV

The fire apparently started when construction crews were heating up a tar-like material, according to an M.D. Anderson spokesperson.

HFD investigators are working to confirm that.

The new Pickens Academic Building, in the 1400 block of Pressler near Braeswood, is scheduled to open in the spring of 2008.

It was the second major fire Thursday afternoon.

A few hours before the Med. Center fire, a big transformer fire knocked out power to 17,000 people near the Southwest Freeway and Buffalo Speedway.

Many businesses had to shut down, schools went on lockdown and traffic was a mess.

That blaze was brought under control and most of the power has been restored.