Salt Lake City Fire Battalion Chief Mike Andrew said the smell of smoke that filled LDS Hospital on Thursday night was caused by some insulation that caught fire in a mechanical area on the ninth floor. Patients were not evacuated and little damage was caused by the fire, which was not visible, Andrew said.

Crews were called to the hospital in the Avenues neighborhood about 5:10 p.m. on a smell of smoke. welders accidentally sparked the fire when they drilled through wood and concrete. The smoke traveled through the hospital's ventilation system. Fire crews worked well into Thursday night, cutting through walls and concrete, before finally finding the source of the blaze.

Crews were called to the hospital earlier in the day on a complaint of smoke in the same area, but the smoke was less pronounced at that time, Andrew said.

Nate Carlisle