‘Do you hide or do you run?’

A heavily armed man opened fire on his co-workers at a Wisconsin software company yesterday, seriously wounding three people before being fatally shot by police as employees ran from the building or hid inside, according to investigators.

Middleton Police Chief Chuck Foulke said officers shot the man within eight minutes of receiving calls about an active shooter at WTS Paradigm. Foulke said the man was armed with a semiautomatic pistol and extra ammunition, and fired at officers before he was shot.

Foulke said three people were seriously injured during the attack, while a fourth person was grazed by a bullet.

‘‘I think a lot less people were injured or killed because police officers went in and neutralised the shooter,’’ Foulke said.

The police chief said the motivation behind the attack was unclear and investigators didn’t yet know whether the gunman targeted his victims. He didn’t release the suspect’s name but said he was an employee of WTS Paradigm and lived in nearby Madison.

Foulke said the investigation was ongoing but noted: ‘‘We have reason to believe the suspect was heavily armed with a lot of extra ammunition, a lot of extra magazines.’’

Judy Lahmers, a business analyst at WTS Paradigm, said she was working at her desk when she heard what sounded ‘‘like somebody was dropping boards on the ground, really loud.’’ Lahmers said she ran out of the building and hid behind a car.

She said the building’s glass entrance door was shattered.

‘‘I’m not looking back, I’m running as fast as I can. You just wonder, ‘Do you hide or do you run?’’’ she ssaid.