A toxic chemical spill at the Merrill Engineering Building on the University of Utah campus prompted an evacuation Tuesday night while crews cleaned up the material.

The chemical mercaptoethanol, a toxic substance that is highly explosive, apparently spilled in the first floor on the building that houses two nuclear reactors, officials said.The hazardous-materials team from the Salt Lake Fire Department, along with two fire trucks and police, were at the scene clearing people out of the building shortly after 7:30 p.m.

Crews cleaned up the spill, which police Lt. Tom Brown said was the size of a 1-foot puddle, and vented the fumes. No one was injured.