Four police officers and one transit officer are dead following a shooting in Dallas that took place during a protest staged over the deaths of Alton Sterling and Philando Castile at the hands of police officers.

The peaceful protest, which was formed over the deaths of Sterling in Baton Rouge, Louisiana on July 5 and Castile in Falcon Heights, Minnesota on July 6, suddenly turned violent around 9 p.m. when snipers opened fire, reportedly targeting white police officers. By the time it had ended, four officers were dead as well as a Dallas Area Rapid Transit (DART) officer, and nine additional people were wounded, including seven officers and two civilians. One of the suspected shooters was also killed following a stand-off with police at a downtown garage.

According to the Dallas Morning News, three other suspects are in police custody but are refusing to cooperate.

The shooting was the deadliest day for law enforcement since September 11, when 72 were killed.

In a statement to the press earlier this morning, Dallas Police Chief David Brown expressed upset over the situation, and said that the violence between police and civilians needed to come to an end.

"We're hurting, our profession is hurting," he said. "There are no words to decribe the atrocity that occurred to our city. All I know is that this must stop, this divisiveness between our police and our citizens."

He also revealed in an even earlier conference new details about the exchange in a parking garage with the suspect who was later killed, where the person claimed to be working alone and said he wanted to kill white officers.

"He has told our negotiators that the end is coming and he's going to hurt and kill more of us-meaning law enforcement-and that there are bombs all over the place in this garage and in downtown," Brown said. "He said he was not affiliated with any groups. He said he did this alone."

The situation is similar to one that occurred in Brooklyn, N.Y. back in 2014, following the deaths of Michael Brown and Eric Garner at the hands of white policemen. Officers Wenjian Liu and Rafael Ramos died in that shooting.