FAIRFIELD — Four people have been arrested on drug charges after officers searched a Winter Street house in Fairfield, where they found methamphetamine, other illegal drugs and an explosive device, according to police.

The investigation began Sunday when Sgt. Matt Wilcox and Officer Dakota Willhoite of the Fairfield Police Department went to the home to find Derek Poirier, 40, of Fairfield, according to police. The officers had an arrest warrant for Poirier, who was under bail conditions prohibiting he have drugs, alcohol or dangerous weapons.

Police searched the house and found usable amounts of heroin and methamphetamine, and what appeared to be an improvised explosive device, according to officials.

“The members of the Maine State Police Bomb/Explosives Unit, as well as the Fire Marshal’s Office, were contacted to assist with the device, which was turned over to the Fire Marshal’s Office for further investigation,” according to a statement Officer Casey Dugas released Thursday to the news media.

Fairfield police arrested Poirier on the warrant and charged him with two counts of possession of a scheduled drug and two counts of violation of conditions of release. He is scheduled to be arraigned Dec. 15 at Skowhegan District Court.

Willhoite said he drafted a search warrant Monday and officers from Fairfield and Clinton returned to the Winter Street house to conduct another search. They found three people — Cassandra Smith, 32, of Unity; Charles Carigan, 43, of Fairfield; and William Moody, 44, of Waterville — inside the house, according to police. Officials said all three were in possession of methamphetamine and were arrested.

Smith, Carigan and Moody all had court-imposed bail conditions and are also scheduled to appear Dec. 15 at Skowhegan District Court.