AUGUSTA – A string of overdoses has authorities worried that Maine’s drug users could be buying drugs that are stronger than they think.

Augusta police Detective Christopher Massey said that more than one overdose within hours is a signal to police that a purer, more lethal form could be in the area.

There were three overdoses in Augusta on Wednesday.

Lisa Bickford, 21, and Kyle Hiebert, 23, both of Augusta, died after apparently overdosing on heroin or a related drug, Massey said. The two were in separate locations, at their own homes, and were found within several hours of each other.

Massey would not release the name of the third victim, who is in critical condition at MaineGeneral Medical Center.

He said police won’t know for sure what the victims overdosed on until toxicology reports are completed, which could take up to a month. The three victims could have been mixing medications, or overdosed on OxyContin, a synthetic opiate, he said.

“We want to make sure the public is aware that there may be a possibility of a higher purity of opiate introduced in the central Maine area,” Massey said.

Sgt. Christopher Read, supervisor for the criminal investigation division for the Augusta police, said police have seen an increasing trend of more potent opiates arriving in Maine.

“If a user of these illegal drugs gets used to a certain level and then all of a sudden there’s an increase in potency in the drugs coming from out of state, that poses a serious health threat,” Read said Thursday. “It poses a risk to them that could possibly result in death.”

Lt. William Hayward said Augusta had five confirmed overdoses last year, but that number could be higher.

Bickford’s and Hiebert’s deaths were the first reported in 2004, he said.

Read said the people who fatally overdosed last year all were between 20 and 30 years old.

Along with purer opiates, he said, there seems to be an increase in the abuse of prescription drugs, which are easier for drug users to get their hands on than illegal drugs.

“We obviously take a very aggressive approach to investigating these types of cases,” he said. “These drugs can be very addictive and they can be lethal. The message we want to get out to the youth of our community is, don’t get into this stuff. Stay away from it.”