NORTH ATTLEBORO - About 400 people were evacuated Friday morning from businesses in the North Attleboro Industrial Park after a large cloud of chlorine gas leaked out of Metalor Technologies.

No one was reported injured.

The leak occurred as two workers were changing a 1-ton chlorine tank inside the building and a piece of tubing broke, Fire Chief Peter Lamb said at a press conference.

The workers were wearing protective clothing and breathing equipment and managed to escape without injury, Lamb said.

The incident occurred around 10:15 a.m. and the first arriving firefighters reported a large cloud of mist around the company located at 255 John Dietsch Blvd. Lamb said the chlorine gas, which is an acidic irritant to the eyes and respiratory systems, quickly dissipated in the air.

"This thing moved pretty quickly," Lamb said.

Roads in the area were reopened shortly before 12:15 p.m., about two hours after the incident was initially reported.

Metalor is a precious metals refinery and manufacturing firm and chlorine is used in the manufacturing process.

The North Attleboro division of the company is a gold and silver refinery.

Most of those evacuated worked for Metalor and the nearby Blackinton & Co. Inc.

As a precaution, residents in the nearby Wendy Drive neighborhood were told to stay in their homes with the doors and windows shut while firefighters assessed the emergency, Lamb said.

At least some of the nearby businesses were allowed to return shortly after 11 a.m.

Police and fire officials closed off the industrial park and had ambulances and a bus from the Greater Attleboro-Taunton Regional Transit Authority standing by to help with the evacuation.

The incident was the second involving hazardous materials in the Attleboro area in as many days. Thursday, Interstate 95 in South Attleboro was shut down much of the day because of a leaking tanker truck that spilled 3,700 gallons of jet fuel following a pre-dawn crash with another vehicle.