DIXMONT, Maine (AP) — A standoff that ended with police using a robot to detonate a bomb has raised questions about whether more public oversight is needed.

The June situation was likely the first time Maine police ended a standoff by using a robot to deliver an explosive, the Bangor Daily News reported .

Police said they needed to protect themselves and the public from bullets fired by 61-year-old Michael Grendell, who is hospitalized with serious injuries and faces three felony charges including attempted murder.

But critics say the public should have a say in whether police should adopt military-like tactics and equipment.

"There's been a great expansion in the technology that is available to law enforcement," said Zachary Heiden, legal director of the American Civil Liberties Union of Maine. "That expansion shouldn't happen without public awareness and public oversight because ultimately the police work for us."

The standoff took place at a home in Dixmont, a small community about 23 miles (38 kilometers) east of Bangor.

Grendell on June 27 shot a handgun at a friend, who was uninjured but called police the next day in hopes of getting Grendell help, according to police.

An hourslong standoff began when police arrived at Grendell's home. Grendell declined to walk away from his home when asked by police.

Grendell didn't acknowledge officers for hours until police drove an armored vehicle up and smashed one of his windows early June 29, according to police reports reviewed by the Bangor Daily News. Grendell then began to shoot occasional rounds at police over the next four hours.

"Not surprisingly, Mr. Grendell was terrified and began firing," said Grendell's attorney David Bate in a statement.

Police planned to use a robot to explode a wall inside his home to minimize potential danger to personnel. Police maneuvered the robot to a window, Grendell shot at the robot and police detonated the explosive.

Grendell emerged from the explosion and picked up a rifle, and police shot him in the face and torso when he didn't drop the gun.

Bate claimed that police actions "appear to have inflamed a potentially volatile situation. Law enforcement obviously underestimated the danger and strength of their bomb that they deployed against a mentally ill citizen."

Police haven't disclosed what kind of explosives they used.

It's rare for police to use explosives against civilians. Dallas police in 2016 used a robot to place an explosive that killed a man suspected in the death of five police officers.

"It was a significant event, and our hand was forced in some ways by Grendell's continuing to engage in shooting from his residence. At a certain point we needed to take steps to protect our officers and the neighbors," State Police Chief John Cote said.

It's an issue that lawmakers could take up, said Democratic Rep. Charlotte Warren, who co-chairs the Legislature's criminal justice committee. "How often is this used? What is the protocol for when this is used?" Warren said.