NOTE: The material in this story comes from CNN. EverythingLubbock.com expects updates to be posted at this link.

Shooters killed five officers during protests against police in downtown Dallas, marking the deadliest incident for U.S. law enforcement since September 11, 2001.

The gunfire started Thursday night as demonstrators marched against the shooting deaths of two African-American men by police in Louisiana and Minnesota.

A total of 11 officers were shot.  Dallas Police Chief David Brown said it’s unclear how many suspects were involved, but three people were in custody.

Dallas police negotiated and exchanged gunfire with a suspect for hours at a parking garage in downtown. That suspect is dead, a law enforcement official told CNN. The official did not say how the suspect died.

“The suspect told our negotiators that the end is coming,” Brown said. The suspect at the garage also told negotiators more officers are going to get hurt, and that bombs are planted all over downtown Dallas.

Police found no explosives during primary and secondary sweeps of the area, Dallas police Maj. Max Geron said Friday morning on Twitter.

Two of the shooters were snipers, who fired “ambush-style” from an “elevated position,” Brown said.

In summary, five officers were killed, seven more were wounded and two civilians were also hurt.

Witness Clarissa Myles said she was eating at McDonalds when the chaos began.

“Everyone was screaming, people were running,” she said. “I saw at least probably 30 shots go off.”

“I was walking next to the officer who was helping with the protest, all of a sudden I saw six to eight shots,” one witness told the station. “It looked like two officers went down.”

Another witness who was at the protest told the station he heard multiple gunshots.

“Whoever was shooting had an assault rifle — and I know guns. The shots were in rapid succession,” the witness said.

Video showed numerous police officers crouching behind vehicles. Others approached a location holding protective shields.