Tong died from “firearm-related trauma,” WISC reported, attributing the medical examiner.
Investigators have still not released a motive in the attack.
Update 9:00 p.m. EDT Sept. 19: The Middleton company where a shooting unfolding Wednesday morning issued a statement thanking police and emergency crews for their quick response, according to WKOW.
“The entire WTS Paradigm team is shocked and heartbroken by the incident that occurred today at our Middleton office,” company officials said.
“Our deepest thoughts are with all of our staff and their loved ones.”
Update 5:15 p.m. EDT Sept. 19: Police in Middleton, Wisconsin, have not released the identity of the suspect in a shooting at the software company WTS Paradigm Wednesday morning that injured four people, except to confirm that he was an employee at the company.
Police Chief Chuck Foulke also told reporters during an afternoon press conference that investigators do not know the motive for the attack.
Foulke did say the suspect was “heavily armed with extra ammunition and magazines,” according to WISC-TV.
Four people were injured, three of them are hospitalized and a fourth was treated for a “grazing injury” and released, Foulke said.
The investigation is continuing.
Update 3:10 p.m. EDT Sept. 19: Middleton police Chief Chuck Foulke confirmed Wednesday afternoon that the gunman, who has not been identified, died of his injuries, WISC-TV reported.
Foulke said three other people were injured before police responded to the shooting Wednesday morning and engaged the suspect.
Police are expected to provide additional information about the incident at a news conference scheduled to take place at 4 p.m.
Update 2:30 p.m. EDT Sept. 19: Middleton police Chief Charles Foulke said the unidentified gunman who opened fire Wednesday morning at WTS Paradigm was among the four people injured in the attack.
Foulke did not identify the shooter, who was confronted by police after they were called to the building around 10:25 a.m.
“He was shot by officers and he is also at a local hospital,” Foulke said. “The main thing we can say right now is the suspect was neutralized, is at a local hospital, and that the public is no longer in danger from this incident.”
The chief said police believe the injured gunman is the only suspect in Wednesday’s shooting.
Authorities are expected to provide another update on the investigation at a news conference scheduled for 4 p.m. local time.
Update 1:50 p.m. EDT Sept. 19: Judy Lahmers, who works as a business analyst at WTS Paradigm, told WITI that Wednesday morning's shooting was "totally unexpected."
“We’re all software people,” she told the news station. “We have a good group.”
She said she heard what sounded "like somebody was dropping boards on the ground, really loud," on Wednesday morning and ran from the building. She took shelter behind a car, according to WITI. At some point, she said the glass door to the building shattered.
"I'm not looking back, I'm running as fast as I can," she told WITI. "You just wonder, do you hide or do you run?"
Hospital and city officials said at least four people were injured in Wednesday morning shooting, although their conditions were not immediately known. Citing officials with the Madison School District, WKOW reported the suspected shooter was in custody after the incident. City Administrator Mike Davis told The Associated Press that the unidentified shooter was also injured.
Update 1:35 p.m. EDT Sept. 19: City Administrator Mike Davis told The Associated Press that none of the four people injured in Wednesday's shooting at the WTS Paradigm office in Middleton were fatally wounded. The extent of their injuries was not immediately known.
Davis told the AP that the person suspected of opening fire Wednesday morning was also injured. A lockdown of the building where the shooting took place was lifted a few hours after the incident, according to the AP.
Update 1:25 p.m. EDT Sept. 19: A person has been taken into custody after a reported shooting at a Wisconsin office building, WKOW reported, citing a letter from the Madison School District.
"I have confirmed with the Madison Police Department that the shooter has been taken into custody," Joseph Balles, the coordinator of school safety and security for the school district, said in the letter, according to WKOW. "Police are still searching this particular building for any other threats."
Police confirmed few details in the immediate aftermath of the shooting, which was reported around 10:25 a.m. local time. At least four people were injured in the incident, UW Health officials told WISC-TV.
Police have not commented on any injuries associated with the shooting.
Update 1:10 p.m. EDT Sept. 19: Officials with Wisconsin's UW Health told WISC-TV that four people were taken to the hospital after a reported shooting at an office building on Deming Way.
Their conditions were not immediately known.
The Milwaukee Journal Sentinel reported earlier Wednesday that the shooting took place at the office for Esker Software, however, the company's director of sales, Dan Reeve, told WISC-TV that the shooting happened next door. The shooting took place at the offices for software company WTS Paradigm, according to witnesses.
Police have not confirmed any injury reports. Officials continue to investigate.
Original report: In a notice posted around 11:15 a.m. local time on Nixle, Middleton police warned that they were responding to "an active shooter in the 1800 block of Deming Way."
They asked people in the area to lock their doors, stay inside and shelter in place “until further notice.”
Officials with the Dane County Communications Center confirmed to WGBA that officials were called around 10:25 a.m. The Milwaukee Journal Sentinel reported that the shooting allegedly took place at an office building on Deming Way that houses Esker Software and other companies.
Few details were immediately available on the incident. Officials with the Bureau of Alcohol, Tobacco, Firearms and Explosives said the agency was also responding to the report Wednesday.
Authorities continue to investigate.
Check back for updates to this developing story.