The Latest on the aftermath of the shooting of police officers during a protest in Dallas (all times local):

8 a.m.

Detroit police have arrested four men over Facebook postings that the city's police chief says amount to threats against officers.

The Detroit News reports (http://detne.ws/29xvuqS ) that one of the men is accused of urging people to kill white officers.

Chief James Craig said Sunday that the department's counter-terrorism unit found that posting while monitoring social media. He says "while it's been established that hate speech is protected by the First Amendment, we're talking about people specifically saying on Facebook they want to kill white police officers."

Police say two other posts about shooting officers were scrutinized. Craig says two of the men were released and two were jailed on unrelated warrants.

The arrests follow the fatal shooting of five officers in Dallas. Craig has said his officers are on alert after the shootings.

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1:01 a.m.

The Dallas police chief says the suspect in the deadly attack on officers taunted authorities during two hours of negotiations, laughing at them and at one point asking how many officers he had shot.

The chief and the county's most senior elected official also said Sunday that Micah Johnson had larger attack plans and possessed enough explosive material to inflict far greater harm.

Dallas Police Chief David Brown says Johnson, a black Army veteran, insisted on speaking with a black negotiator. The chief says he also wrote in blood on the wall of a parking garage where police cornered and later killed him.

The shootings marked the deadliest day for U.S. law enforcement since the Sept. 11, 2001, terrorist attacks. Five officers were fatally shot just a few blocks from where President John F. Kennedy was slain in 1963.