JACKSONVILLE, Fla. -- Fire-Rescue personnel and area medical personnel geared up for mass casualties when an industrial accident at a Baymeadows manufacturing facility Monday morning leaked a small amount of radiation.

The Unison Industries building in the 7500 block of Baymeadows Way was evacuated and police blocked streets in the area after a cylinder of krypton gas exploded in the facility about 10:45 a.m.

A spokesman for Unison said no radioactive material was released, but when members of the hazardous material team reported picking up radiation inside the building with their Geiger counters, a level 3 alert was declared.

One employee who received cuts and burns in the initial explosion was transported to St. Luke's Hospital.

About 500 employees who work at Unison's Baymeadows Way facility were evacuated.

About 15 other employees were taken to area hospitals and were treated for high blood pressure, anxiety and other complaints.

The fire department began checking employees' radiation levels and about 20 people were put through a decontamination process before radiation levels dropped to between 30 and 60 parts per million.

Fire-Rescue spokesman Tom Frances said 200 parts per million is considered unsafe.

"We are not faced with a life-or-death situation here," Francis said on Channel 4 at noon.

Twelve ambulances were called to the scene and Shands-Jacksonville Medical Center prepared for up to 100 patients. Frances said that three employees were transported to Baptist Medical Center, seven were taken to St. Luke's Hospital and five went to Shands.

None of them suffered any effects of radiation exposure, Frances said.

Employees not requiring medical attention were put on Jacksonville Transportation Authority buses to wait.

An expert in nuclear physics from the Mayo Clinic to consult with firefighters and was going to work with Unison on making sure the facility safe for the employees to return.

Officials said the health risk from krypton gas was minimal -- similar to the risk from exposure to an X-ray.

Unison's Web site says the company makes aviation parts, with power condition and control units made at the company's Jacksonville facility. The company also makes parts for Tomahawk missiles, although not at the Jacksonville facility.

Unison spokesman Wayne Moles said he was not aware that any product used in their facility had a high radiation risk.

"That gas primary involves hydrogen, nitrogen,other elements, but has a small amount of krypton 85 in it, and that may have been the source of the readings that the fire department found," Moles said.

The company released a statement late in the day saying the facility would reopen Tuesday.