A 47-year-old man who was shot twice by an unknown attacker while he slept early Monday in his Scarborough home remained hospitalized Tuesday, but his medical condition was upgraded from stable to good, police said.

Police have said that Bruce Glidden appears to have been targeted, though they offered no motive for the attack and have yet to identify any suspects.

Glidden’s armed attacker or attackers are still at large, and police have cautioned residents to lock their doors and be aware of their surroundings. But while police did warn the public to be cautious, they also said they believe the attack was specific to the Glidden family.

Scarborough police Sgt. John O’Malley said Tuesday afternoon that Glidden was still hospitalized at Maine Medical Center in Portland and that he still had no word on when Glidden would be released.

“We’re doing everything we can to protect him, but we can’t confirm whether he was the target or not,” O’Malley said.

Glidden is an owner of Glidden Roofing Corp. in Scarborough. Bill Cashman, another partner in the family business, declined to comment Monday, saying police had advised him not to speak to the media because of the ongoing investigation.

O’Malley would not say Tuesday what kind of weapon was used in the shooting. He also would not say whether police found footprints or tire tracks in the snow that they could use to identify the culprit or culprits.

“There were several pieces of usable evidence at the scene,” O’Malley said, though he would not be more specific.

Glidden’s wife, Amy Glidden, reached at home on Monday, declined to comment on her husband’s shooting.

Police have yet to determine whether the attack on Glidden may have been motivated by some animosity toward another member of his household, O’Malley said. Amy Glidden and the couple’s two teenage children were also at their home on Ash Swamp Road at the time of the shooting, around 1:30 a.m. on Monday.

Deputy Police Chief David Grover said at a news conference Monday that Glidden was asleep in the family room of the house when at least one intruder entered the home through an unlocked door and shot him twice. Amy Glidden and their children were asleep in other parts of the house and were not injured or threatened, he said.

The windows of a car owned by the Gliddens were broken at the time of the shooting, police said. The windows were broken with an object, not by gunfire, Grover said Monday.

A resident of the home called 911 to report the shooting around 1:30 a.m. Monday. Grover wouldn’t say who called.

Grover wouldn’t say why police believe the family was targeted. No weapon was recovered from the scene and none of the family’s possessions appeared to have been taken from the home.

O’Malley said investigators heard that a window on Glidden’s work truck had been smashed about a week before the shooting, but no police report was made at the time. Police are considering that detail as they continue to investigate, he said.

“We’re checking on every rumor and every lead,” O’Malley said.

Glidden has no criminal record, according to a Maine State Bureau of Identification database. State courts have no record of any protection-from-abuse orders taken out by or against Glidden.

Glidden Roofing Corp. is listed as a co-defendant, along with Carlisle Syntec Inc. of Pennsylvania, in a lawsuit filed in Kennebec County Superior Court in 2015 by Granite State Insurance Co. Details about that lawsuit were not available at the courthouse in Augusta on Tuesday.

Police encouraged anyone with information about the shooting to call the business line of the Scarborough Police Department at 883-6361 or the anonymous crime tip hotline at 730-4386.