A day after Upper Merion police officers opened fire at an armed suspect inside a crowded parking garage at the King of Prussia Mall, authorities were tight-lipped about the suspect's identity and other details as they investigated the afternoon shooting.

"I can assure the public that this investigation will be fair, and it will be thorough," Montgomery County District Attorney Kevin R. Steele said Monday afternoon. "We will determine the circumstances that led up to the shooting and whether the decision to use deadly force is lawful in that situation."

The District Attorney's Office is handling the investigation, per state policy regarding officer-involved shootings. The involved officers, whose names have not been released, will be on administrative leave until the investigation is concluded.

As of Monday afternoon, the suspect was being treated at Paoli Hospital, where he was listed in serious condition with multiple gunshot wounds. His identity had not been made public and he had not been charged.

Sources have identified the suspect as Kalin Jackson, 23, of New Castle, Del.

Upper Merion police encountered the man, suspected in a string of recent armed robberies, just before 4 p.m. Sunday on the second floor of the multi-level Green Deck parking garage, which connects to the Nordstrom and Lord & Taylor department stores.

Upper Merion Police Chief Thomas Nolan said the garage was "crowded" with mall patrons. No shoppers or employees were harmed, mall officials said.

Authorities declined to comment on how they tracked the suspect to the garage, but when they approached him, he allegedly sped off in a maroon 2012 Kia Sorento, ramming two police cars and attempting to hit officers on foot.

Authorities have not said how many officers were involved in the shooting or exactly when or how many shots were fired.

Nolan said that on Saturday, about 3:30 p.m., the man is suspected of robbing a woman in the same King of Prussia Mall parking garage at gunpoint, jumping into the rear seat of her car as she entered it, and holding a 9mm gun to her head as he demanded her purse. He allegedly fled in a car matching the description of the 2012 Kia Sorento.

The vehicle is believed to have been carjacked on Friday in Claymont, Del., where an 87-year-old man was robbed and kidnapped. The victim was driven around at gunpoint before the gunman dropped him off near I-95 and fled.

The shooting on Sunday erupted near the same location where the woman had been robbed about 24 hours earlier.

A 9mm handgun recovered from the passenger seat of the stolen vehicle on Sunday is believed to have been the weapon used in the Saturday holdup, the Friday carjacking and two other Delaware incidents.

Some of those in and around the sprawling mall — which has more than 400 stores and the most retail space of any mall in the country — were rattled by the shooting but by Monday, but other shoppers said the incident was uncommon and not particularly troubling.

Shaina Bloom of Collegeville said on Facebook that she parked in that garage after her lunch break on Sunday and was walking back to her job at a store in the mall when shots rang out.

“I heard the shots, but I didn’t know that that was what was happening,” Bloom said. “I thought something fell off of a truck in the loading dock or something but when I got back to the store, they had already been notified of the shooting.” 

Bloom said the mall remained open but she, her coworkers, and some clients went to a back room of the store.

Terra Droneburg of King of Prussia also took to Facebook, saying she was leaving the garage around the time of the shooting.

"Scary!" Droneburg said. "We saw the lights on the parking deck above where we parked but didn't realize that's what was going on."

Kate Lewis, a South Philly resident who works in Malvern, said on Monday she generally feels safe shopping at King of Prussia.

"I've never felt unsafe coming here and I've come at night many times," Lewis said.

Staff writers Emerson Max and Jeremy Roebuck contributed to this article