Eleven police officers were shot by at least two snipers in Dallas Thursday night during a protest over police brutality, leaving five officers dead and wounding six, throwing the city into chaos and turning parts of downtown into a massive crime scene by Friday morning.

Dallas Police Chief David Brown said the snipers had opened fire on officers from “elevated positions” during the protests. A civilian was also wounded.

Three suspects were taken into custody, including a woman.

Amateur video appears to show Dallas gunman

A fourth suspect exchanged gunfire with police in a tense, hourslong standoff with police overnight, but that confrontation ended early Friday morning, according to a city spokesperson. Sana Syed, a Dallas public information officer, said she couldn’t confirm the status of the fourth and final suspect, but said “the standoff is over.”

The suspect had told police negotiators that “the end is coming,” and that bombs had been placed around the garage and downtown with the aim of killing more law-enforcement personnel, Chief Brown said, adding that he had asked his staff for a plan to end the standoff.

Police are working on the assumption that all four may have been involved in the attack. It appeared the suspects had knowledge of the protest route, allowing them to take up “triangulated” positions above the march and target officers.

Police in standoff with protesters after Dallas shooting

Police were still searching for other suspects overnight, just hours before thousand of workers would fill offices, restaurants and shops in the downtown.

“We still don’t have a complete comfort level that we have all the suspects,” Chief Brown said, adding a search of the area was continuing.

Police and city officials said that large areas of downtown would be closed Friday as police continued their investigation.

An expanded version of this report appears on WSJ.com