(CBS) — Police in the far eastern Canadian city of Fredericton lost two of their own in a shooting incident on Friday morning. Fredericton police confirmed in a tweet that there were “at least four people killed” earlier in the day, and later said two of the dead were officers.

About an hour after the incident began, police said they had one suspect in custody but advised residents that the area would remain “contained for the foreseeable future” amid the ongoing investigation. They did not renew an earlier request for residents to remain in their homes with doors locked, but they also did not rescind it.

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Fredericton is in New Brunswick province, about 50 miles northeast of the U.S. border with Maine.

Residents were warned to “stay in their homes with doors locked at this time for their safety” in an earlier tweet by police. Video from the scene broadcast by Canadian network CBC showed emergency vehicles on Brookside Drive, a residential road.

Rachel LeBlanc, who was sheltering at a daycare center within the lockdown area on Brookside Drive, told CBC she heard gunshots shortly after arriving at work on Friday. She said she heard a “crack, crack, crack, four in a row” in rapid succession. LeBlanc told CBC that the 23 kids in her care were unaware of the ongoing security incident, but that she was nervous as the person in charge of their care.

There was no immediate information on whether there might be additional suspects, or on any suspected motive.

David MacCoubrey, who lives in Fredericton, said he heard about 20 shots fired. He was hiding on his kitchen floor. He awoke in his apartment on Brookside Drive around 7 a.m. local time to the sound of three gunshots about 30 feet from his bed.

MacCoubrey said his apartment complex has four buildings in a square, and it sounded like the shots were coming from the middle of the complex.

He said police have been searching the complex, and he’s been sitting away from windows. He said the police searched his apartment.

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CBS News security analyst Paul Vollis said that based solely on the video from the scene, it appeared the police had established a primary and secondary security cordon area, indicating that they had likely determined the location of the shooter or shooters.