A police officer and three other people were shot and killed when a domestic dispute at a bank escalated into shootings at three locations in northern Wisconsin on Wednesday, investigators said.

A suspect was taken in custody after the shootings, which happened at a bank, a law firm and an apartment complex. Officers, including a Swat team, had a standoff with the suspect for several hours at the apartment site before it ended in a volley of gunfire at about 5pm.

Authorities took no questions in a brief media conference late on Wednesday and gave no details on the four victims or the suspect. They said there was no remaining threat to the public. Jason Smith, a deputy administrator for the state Department of Justice’s division of criminal investigation, said more than 100 officers were investigating and more information would be released on Thursday.

The violence unfolded in a cluster of small towns south of Wausau, about 90 miles (145km) west of Green Bay. The officer worked for Everest Metro, a small, 27-officer force that serves Schofield and Weston.

Everest Metro chief Wally Sparks offered his condolences to all the victims and their families and asked the public to “please keep them in your prayers and be with our officers”.

The first shooting was reported shortly after midday at Marathon savings bank in Rothschild. Officers responding to a reported “domestic situation” at the bank arrived to find two people had been shot. They said the suspect was gone when they arrived.

A second call came about 10 minutes later from the Tlusty, Kennedy and Dirks law firm in nearby Schofield. The third shooting happened at 1.30pm from an apartment complex in Weston.

A woman who lives in the complex said she looked out of her apartment window at the complex at about 1.15pm. to see a squad car approach, and a few seconds later heard a gunshot and saw the officer fall. Kelly Hanson, 21, said she saw other officers put the wounded policeman in an armored Swat vehicle and take him away.

“I thought, what is going on? I know what a gun sounds like, and thought ‘This isn’t good’,” Hanson said. She said she stayed in her apartment until about 4.45pm when she heard a volley of about 10 shots. Authorities eventually let her leave her apartment. “It’s tragic that had to happen, but I think they did a good job out here today,” Hanson said.

Swat members entered the apartment building about 2.30pm, the Wausau Daily Herald reported. Nearby schools and a hospital went into lockdowns that were later lifted.

Susan Thompson, a resident of the building, told the newspaper she heard gunshots and someone scream. As she left her apartment, police called to her to get inside and lock her doors. Thompson, 21, said she had her two-year-old daughter in the apartment. Officers later came to her door and helped her and her daughter outside, she said.

Omar Sey, 31, who said he had just moved to the apartment complex, learned of the shooting after he arrived home to find dozens of squad cars outside. Sey, who said he had moved to Wisconsin from Gambia, said he didn’t understand why such things happen in America.

“This is crazy,” he said. “You have everything at your disposal. Why don’t you make your life better instead of engaging in this.”