ALFRED — The York County Sheriff’s Office and Kennebunk police have arrested three people and seized guns and $20,000 worth of cocaine and heroin in a joint operation targeting what police described as a mid-level dealer.

The drugs were being sold from a house about a quarter-mile from Sea Road Elementary School, police said.

At a joint news conference Friday morning at the sheriff’s office in Alfred, the agencies displayed the items seized when they executed a search warrant at 5 Sea Road in Kennebunk on Wednesday night. The seizure included $10,000 in drug proceeds, 8 ounces of cocaine, 40 grams of heroin, a number of Oxycontin pills, 12 rifles and two handguns.

The material also included notebooks used as business ledgers, said Sheriff Maurice Ouellette. More arrests are expected. Investigators are trying to determine the source of the drugs.

“We’ll see if we can work up the ladder, so to speak,” Ouellette said, adding that most of the drugs sold in Maine arrive from other states.

The investigation started with a tip provided to a sheriff’s deputy who contracts with Shapleigh, Ouellette said. Local police and sheriff’s deputies were assisted by the U.S. Drug Enforcement Administration and the federal Bureau of Alcohol, Tobacco, Firearms and Explosives.

Kennebunk Lt. Daniel Jones said the operation was a good example of cooperation between local and federal agencies to fight drug crime, which is not constrained by municipal boundaries.

Jones said the operation was about a mile from downtown and the police station. Because the operation was not selling to street-level users, there was not much traffic at the house and it did not draw attention.

Arrested in the operation were Cyrus Gould, 32, of 5 Sea Road, charged with aggravated drug trafficking; Walker Donovan, 24, charged with drug trafficking; and Christian Ness, 42, of Wells, charged with drug possession.

Gould is being held at the York County Jail on $25,000 bail, Donovan is free on $1,000 bail and Ness is being held on $500 bail.

Ouellette said the rifles, which may have been owned for hunting, were less concerning than the confiscated derringer and snub-nosed pistol.

Chief Deputy William King said the bust was not the biggest in recent history, but believes it would have grown, without intervention. He also said that the operation is unusual in the wide variety of drugs seized, including marijuana, Suboxone and other pills police have yet to identify.

“This was the Baskin-Robbins of drug houses,” King said.