Four firefighters were hospitalized early this morning after inhaling nitric acid, a toxic and potentially explosive chemical, at a metal plating company in Lawrence, said acting Lawrence Deputy Fire Chief Jack Meaney.
The firefighters were treated at Lawrence General Hospital and released this afternoon, he said.
They responded to a report of a chemical release at 22 Ballard Road around 1:30 a.m., said firefighter Mike Forensi. The building is owned by N-Tek Inc., which was closed when the incident occurred.
A man who answered the phone at a number listed for N-Tek Inc declined to comment this afternoon.
The chemical release prompted firefighters and a state hazmat team to close down a section of Ballard Road near the building and evacuate two homes in Lawrence and one in Andover, Meaney said. The residents have since been allowed to return to their homes.
The hazmat team remains at the scene this afternoon to decontaminate the building before turning it back over to the owner, Meaney said.
The incident is under investigation, although at this time authorities do not believe the chemical release to be suspicious, he said.Todd Feathers can be reached at todd.feathers@ globe.com. Follow him on Twitter @ToddFeathers.