PORTER – Maine State Police used tear gas and 30 minutes of negotiations Monday to convince a 27-year-old man and his mother to surrender after a 13-hour standoff.

The standoff began when it was reported that Jesse B. Leahy fired shots at those attending an earlier party in Porter.

Oxford County Sheriff’ Department Capt. James P. Miclon said Leahy, who has addresses in Boston and Colorado, was preliminarily charged with criminal threatening with a dangerous weapon and aggravated assault. He also had a warrant out for failure to appear for an operating under the influence charge.

The mother, Donna Leahy, 51, was charged with obstructing governmental administration and hindering apprehension.

Miclon said an 18-year-old Porter man was the only person injured in the events when he was allegedly pistol-whipped by Leahy at a post-party fracas that led to the standoff.

He said the Porter teen was treated and released at a nearby hospital. The name of the victim is not being released at this time.

Miclon said that shortly after midnight on Monday his department received multiple 911 calls in the Bridge Street and River Street area off Route 25 near Parsonsfield.

“The original call came in saying there were multiple gunshots and that two people were shot and were down,” Miclon said.

The Sheriff’s Department sent three deputies and Maine State Police and York County Sheriff deputies also answered the calls.

Miclon said while en route lawmen learned that there were multiple gunshots fired, but nobody was hit. It was reported that one man was pistol whipped and received severe blows to the head.

It was also reported that Leahy did the shooting and he went into his mother’s residence at 13 Bridge St.

Deputies soon cordoned off a half-mile area around the Bridge Street house.

Miclon said a background check on Leahy revealed that he had been involved in other incidences involving firearms.

“Based on that information, the fact that he had committed a felony and that we believed he had one or more weapons inside that house, we called the Maine State Police Tactical Team,” Miclon said. “We tried to contact him on the telephone and using a PA (public address) system. But he would not answer.”

He said after the tactical team arrived, contact was tried with no success by using phone, public address, e-mail and faxes.

At about 2 p.m. Troopers fired tear gas into the single family home.

“He finally answered the phone,” Miclon said. “The (tactical team) negotiator established a dialogue and he finally surrendered at 2:30.”

Miclon said the incident started when party-goers took Leahy from the house for being disrespectful to the woman hosting the event. He said Leahy was escorted out and not manhandled. Leahy then went home and came back with a pistol.

“He threatened everyone at the party and then fired shots close enough at their feet to kick up dirt in their faces,” Miclon said. “When he ran out of ammo he struck a person in the head.”

Miclon said there were some juveniles at the party, but the majority involved were adults.

Leahy had been visiting his mother.

Miclon said two firearms were found in the search, but he needed to wait for a lab report to determine if it was the gun used in the shooting.

Brian Tripp from Maine Warden Service and his dog, Molly, who is trained to sniff out firearms, helped in the search.

In all, Miclon said eight Oxford County deputies, a dozen troopers and six York County deputies were on the scene with the tactical team.

At 4:30 p.m. The special evidence team of the Oxford County Sheriff’s Department was still gathering evidence.

“We started processing the scene as soon as he was grabbed,” Miclon said.

Leahy was in the Oxford County Jail with no bail set. His mother’s bail was $500 cash.