WATERVILLE — The Waterville man who fired a handgun last weekend at a party at Colby College told police the incident began when he was hit in the head with a bottle by a man with whom he had fought years earlier, according to a police affidavit obtained Thursday.

The affidavit was based on an interview Waterville police conducted with the man they have identified as the shooter, Andrew Gifford, 24. The gunfire occurred early Saturday morning at the college’s Alfond Apartments off Washington Street.

No one was injured in the shooting, which occurred in a hallway filled with people attending a large party, police said.

Gifford was taken to a hospital for a head wound, and was later arrested and charged with reckless conduct with a dangerous weapon.

He was at the Kennebec County Correctional Facility in Augusta, where his bail had been lowered to $7,500 from $10,000, according to a jail spokesman. Gifford is scheduled to appear June 12 at Kennebec County Superior Court, also in Augusta.

Gifford is the only person who has been charged in the incident, according to interim police Chief William Bonney, who said Thursday that the case remained under investigation and police were consulting with the district attorney’s office for Kennebec and Somerset counties about additional charges that could be filed.

The party at which the shooting occurred is known as “Doghead,” and is held by students annually on the closest Friday to St. Patrick’s Day, according to a Colby student. Gifford and the others involved in the altercation were not Colby students, police said.

Waterville police Detective Duane Cloutier collected evidence at the scene and later interviewed Gifford at the police station.

Cloutier wrote in the affidavit that Gifford had told him the man who is alleged to have hit Gifford in the head before the gunfire dated Gifford’s foster sister about five years ago. The ex-boyfriend was reportedly “aggressive” with Gifford’s foster sister, and he and Gifford had fought over it at that time.

Gifford told Cloutier that since then, he has felt he “always has to look around and cover his back,” which is why he carried a handgun, according to the affidavit.

Gifford also told Cloutier that he had stopped drinking, but began drinking beer again over the past two to three weeks.

Gifford told Cloutier a friend had asked him last Friday to go to bars in Waterville. The friend later told Gifford about a party at Colby, so they and another friend drove to the college’s apartments. Gifford said they were following a vehicle in which his foster sister’s ex-boyfriend was traveling.

At the party, Gifford did not consume alcohol or “weed” and was helping to check IDs at the door when he turned around and saw the ex-boyfriend, he told police. He said that is when the man hit Gifford in the head with what Gifford thought was a vodka bottle.

“Andrew told me that the whole reason he carries (a handgun) is for situations like that,” Cloutier wrote in the affidavit.

Gifford told Cloutier that when he was hit in the head, he fired a Ruger 9 mm handgun two or three times at the man who had struck him with the bottle. The man was 5 or 10 feet away, he said. The rounds hit walls in the hallway.

A man who had helped Gifford after the gunfire told Cloutier that after Gifford fired the gun, two people began yelling at Gifford and one of them flashed a handgun and punched Gifford, after which Gifford reloaded his handgun, according to the affidavit.

The man helping Gifford told the two people to leave and then took off his shirt to stop the bleeding on Gifford’s head. Colby emergency medical services then arrived.

Police received a 911 call at about 1:30 a.m. Saturday, with someone at the campus apartments reporting shots were heard at the building and blood was on the floor, according to the affidavit. Officers from Waterville and Winslow responded.