SOMERSWORTH — Firearms, drugs and drug paraphernalia were found at 219 Green St., the site of a 17-hour standoff that started Thursday evening, police announced on Monday night.

Police said, via a Facebook post, a search of the residence yielded an AR-15 .223 rifle, a shotgun and a revolver, as well as replica weapons, including a replica Sig-Sauer AR-15 rifle, three airsoft pistols and two crossbows. All of the weapons and replica weapons were seized.

Also seized, according to police, was quantity of crack cocaine, loaded heroin needles and other drug paraphernalia.

“This is still an active investigation, so please understand that to assure the integrity of the investigation remains there are things we will not address,” Chief David Kretschmar said via a Facebook post on Monday night.

Police said a search warrant was applied for and granted for one apartment at 219 Green St., (which contains four units), specifically to search for drugs, namely heroin. While preparing the warrant, police learned that a person with prior arrests for firearms violations was present at the apartment, and that there was an AR-15 rifle in a second apartment, and that there was a clear connection between the two apartments, police said.

A search warrant for the second apartment was granted. Police then determined a tactical team was required, which led to the closure of Green Street, police said. Others had already been arrested on Thursday and early Friday morning as the operation progressed, police said.

“Our goal is to always execute search warrants in a safe manner, for Law Enforcement Officers, suspects, and any civilians that may be in the area,” the Facebook post said. “We accomplished that in this case, which is a win in our minds.”

Earlier on Monday, police said they are still looking to question Robert Twombly, 39, in connection with the standoff. Police did not say if Twombly was a tenant of the 219 Green St., building.

According to Somersworth online property tax records, 219 Green St., is owned by Glenda E. Castleberry and Leah A. Boyd. Police said it is their understanding that they are in fact the owners.

Police said they do not believe any of the tenants have returned to the house, which was heavily damaged during the standoff. Several windows were broken and police pushed in a door with a State Police battering ram, which was put in place at about 11:42 a.m. and was facing the front door of the residence on Friday.

Police arrested Samantha J. Beyer-Morele, 27, on a probation/parole warrant and Brett Turgeon, 29, for violating probation/parole. Both reside at 219 Green St., Apt. B.

Others arrested were Brianna Y. Cruz, 19, of 108 Franklin St., Apt. C, in Somersworth, who was charged with possession of a controlled drug (methamphetamine), and Aiyla M. Griffin, 25, of 219 Green St., Apt. B, on a drug possession charge and bench warrant for violation of probation/parole, according to police. Police also said a transient named Christopher Beckwith, 39, was also arrested and accused of absconding from drug court.

In addition to the battering ram, several heavily armed and armored law enforcement officers wearing gas masks were seen entering and leaving the residence several times. A small bomb-disposal robot was also on the scene.

At about 12:22 p.m. on Friday a K9 unit and about seven members of the Seacoast Emergency Response Team entered the residence. Three of them came out later without a suspect.

Throughout the standoff, police could be heard intermittently using loudspeakers or bull horns to attempt communication with someone inside the dwelling, trying to talk to a person named “Robert.”

“Robert, this is the State Police. We have a warrant for your arrest. Please come out now and there will be no harm done to you,” said police over an amplification device.

A police sharpshooter in camouflage could be seen on the ground near the scene and looking through the scope of a rifle.