FRANKLIN, N.H. – A man arrested after a raid and explosion at a meth lab was wearing rubber gloves and carrying a laundry basket of chemicals when officers entered the building Tuesday, a police chief said.

The man, identified as Jeremy Clough, 31, lived at the apartment building and was arrested on drug production and sales charges, as was his live-in girlfriend, 33-year-old Rebecca Fields, Tilton Police Chief Robert Cormier said.

The fire errupted after police requested a lockdown at nearby Franklin High School and entered the apartment building around 10 a.m. About 20 people were evacuated from an apartment building next door as a precaution.

When police walked in, Clough “was just starting to cook,” Cormier said. One meth lab was burned, but another found in a storage room behind the apartment was not damaged, he said.

The cause of the combustion wasn’t immediately clear, Cormier said, but the chemicals used to “cook” methamphetamine are volatile if jostled or certain combinations come together.

Both Clough and Fields were also charged with endangering the welfare of children because three children live with them, Cormier said. The children were not present during the arrests and fire; child protection officials were called into the case.

Clough and Fields were to be arraigned today in Franklin, a city of about 8,000 residents 20 miles north of Concord. The Franklin Police Department didn’t know Tuesday whether Clough or Fields had attorneys.

Franklin Police Chief David Goldstein said a Tilton detective had received a tip that a meth lab was operating in the house, and police obtained a search warrant Monday.

On Tuesday, as soon as officers burst through the door of the apartment, “We heard someone yelling, ‘I see a fire! I see a fire!’ ” Goldstein said.

A Franklin police officer was treated for smoke inhalation. No other injuries were reported.