A man who burst into a sign-making business in Minneapolis, Minn., fatally shooting the owner and three others before turning the gun on himself, had been fired from the company earlier in the day, police said today.

Minneapolis police Chief Tim Dolan identified the shooter, who injured at least four others in the Thursday afternoon attack, as Andrew J. Engeldinger, 36, of Minneapolis.

Engeldinger had been fired from his job at Accent Signage Systems earlier in the day, Dolan said. He came back about 4:25 p.m., parked his car, walked into the loading dock area and immediately started shooting people. But it also appeared he may have spared some of his former colleagues.

"It's clear he did walk by some people, very clear," Dolan said.Andrew Engeldinger was fired hours before a shooting at Accent Signage in Minneapolis, Minn., in an incident that left four dead. Engeldinger, who is linked to the shooting, also killed himself. (Finance and Commerce, Bill Klotz/Associated Press)

Investigators who searched a house Thursday night in south Minneapolis where Engeldinger lived found another gun and packaging for 10,000 rounds of ammunition in the house.

"He's obviously been practising in how to use that gun," Dolan said.

Among those killed were businessman Reuven Rahamim, 61, who was the owner of Accent Signage Systems Inc. in Bryn Mawr, a mainly residential neighbourhood on the northwest side of the city, son-in-law Chad Blumenfield said in a statement.

"Other members of the Accent family tragically lost their lives as well, and we mourn their loss," Blumenfield said. He provided no details.

UPS driver Keith Basinski was also killed, the mail service said in a statement Friday. UPS Northern Plains District President Jill Schubert did not say why Basinski was at the Accent offices. She said the company was "profoundly shocked and saddened" at his death.

Authorities have not revealed the names of the others killed.

Chaotic scene

A police summary describes a chaotic scene with multiple 911 calls from the business and one caller saying someone had been shot. When police arrived, they found four people already dead. Dozens of police squad cars and SWAT officers swarmed the area. The first officers on the scene evacuated workers from the business and closed off several blocks.

Of the wounded, John Souter's condition was upgraded from critical to serious as of Friday morning and Eric Rivers remained in critical condition, according to Christine Hill, a spokeswoman for the Hennepin County Medical Center where they were being treated. She had no information on the condition of a third man earlier listed in critical condition.Reuven Rahamim, owner of Accent Signage Systems, a sign-making business in Minneapolis, Minn., that was the site of a workplace shooting Thursday, was among the four victims. (Courtesy of Chad Blumenfield/Associated Press)

A fourth person injured has been treated and released, Hill said Friday.

Late Thursday, police had searched a house in south Minneapolis where the suspected shooter had lived but at that time found "nothing that we know of," police spokesman Sgt. Stephen McCarty told The Associated Press.

There was no evidence of life at that house early Friday except a light in the basement and a boarded-up window with pieces of broken glass nearby. No one responded to a knock on the door.

Thomas Pitheon, a neighbour who lives across the alley, said he came home just after dark Thursday and found "about a dozen" SWAT team members around the house. Pitheon said he had only exchanged pleasantries with the homeowner whom he described as "an average guy" in his 40s.

Company specializes in Braille signs

Rahamim started Accent Signage Systems, Inc. in the basement of his Minneapolis home in the early 1980s, according to the business publication Finance & Commerce. Rahamim said he chose that name because he wanted it to be the first sign company listed in the Yellow Pages.

The small interior signage company specializes in American with Disabilities Act-compliant signs after developing a patented method to create Braille signs for the blind. U.S. Under Secretary of Commerce Francisco Sanchez praised the company for its innovation during a visit to the facility in August, the paper reported.

Rahamim was born and raised in Israel and served as a soldier in the Israeli army before coming to the U.S., Blumenfield said.

"He loved his work and dedicated much of his energy to developing new and greener products," he said by email. "He loved cooking and having people over at his home. He loved spending time with his children and grandchildren and especially loved to take his grandson for bike rides."

Minnesota Gov. Mark Dayton expressed his condolences.

"I deplore this senseless violence," Dayton said. "There is no place for it anywhere in Minnesota."