BATON ROUGE, La. — Officers Montrell Jackson, Matthew Gerald and Brad Garafola were all killed Sunday after being ambushed and shot by a lone gunman in Baton Rouge, Louisiana.
Their deaths have kept the spotlight on a region where the shooting death of Alton Sterling at the hands of police began what has been two weeks of national heartache.
"We as a nation have to be loud and clear that nothing justifies violence against law enforcement," President Barack Obama said after Sunday's attack. "Attacks on police are an attack on all of us, and the rule of law that makes society possible."
Now, police across the country are taking numerous precautions.
The New York Police Department is doubling up all foot patrols and security posts, according to a memo obtained by CNN. Officers are also being instructed to take all meals and personal breaks in pairs.
In Cleveland, the police union is asking Gov. John Kasich to temporarily restrict the state's open carry laws for the Republican National Convention in light of the events in Baton Rouge.
"Only we can prove, through words and through deeds, that we will not be divided," Obama said. "And we're going to have to keep on doing it again and again and again. That's how this country gets united."
'No talking, just shooting'
The shooting Sunday took place around 8:40 a.m. (9:40 a.m. ET) in the city of about 230,000 people, already tense after the high-profile police shooting of Sterling, an African-American man, on July 5.
On Sunday, police received a call of a "suspicious person walking down Airline Highway with an assault rifle," a source with knowledge of the investigation told CNN.
When police arrived, the shooting began.
"There was no talking, just shooting," Baton Rouge Police Cpl. L.J. McKneely said.
The officers who responded to Sunday's shootings killed Gavin Long in a gunbattle after the other officers were ambushed, police sources told CNN. The murder weapon was an AR-15 style semi-automatic rifle, law enforcement sources told CNN.
At an afternoon news conference, local and state authorities, including Louisiana Gov. John Bel Edwards, said Long was thought to be the lone gunman. Earlier reports had said authorities believed there might have been more than one attacker. Edwards described the shooting as an "absolutely unspeakable heinous attack."
The Louisiana State Police said they questioned and released two people in relation to the attack, and no charges have been filed.
Officers Jackson, 32, and Gerald, 41, both worked for the Baton Rouge Police Department.
Gerald had been serving for less than a year and, like Jackson, was assigned to the uniform patrol bureau, according to the department.
Jackson had posted on Facebook on July 8 how physically and emotionally drained he had been since protests had erupted in Baton Rouge after the July 5 killing of Alton Sterling by police.
"I swear to God I love this city, but I wonder if this city loves me. In uniform I get nasty, hateful looks and out of uniform some consider me a threat. ... These are trying times. Please don't let hate infect your heart."
Garafola worked for the East Baton Rouge Sheriff's Office for 24 years, according to Casey Rayborn Hicks, a spokesman for the sheriff's office.
He was 45 years old.
The gunman also critically wounded a deputy who is "fighting for his life," said East Baton Rouge Parish Sheriff Sid Gautreaux. Another wounded deputy and police officer have non-life-threatening wounds, law officers said.
Authorities later identified 41-year-old Nicholas Tullier as an officer in critical condition.
Bruce Simmons, a 51-year-old with 23 years of service, sustained non-life threatening injuries, authorities said.
Authorities say Gavin Long carried out the attack Sunday on law enforcement in Louisiana.
Long, a black man from Kansas City, Missouri, was a Marine who was discharged as a sergeant in 2010.
He left a long trail of information online about his beliefs under the pseudonym Cosmo Setepenra.
Police had been on alert
Since the shooting death of Sterling by Baton Rouge police, the department has worried about threats against officers.
It has been an emotionally charged few days across the country because of the protests stemming from the Sterling shooting and the shooting by police of Philando Castile in Minnesota, plus the ambush on Dallas police officers in which a sniper killed five officers.
"This is an unspeakable and unjustified attack on all of us at a time when we need unity and healing," Gov. Edwards said Sunday in the hours after the Baton Rouge shooting.
Quinyetta McMillon, mother of Sterling's son Cameron, put out a statement through her lawyers condemning the ambush.
"We are disgusted by the despicable act of violence today that resulted in the shooting deaths of members of the Baton Rouge law enforcement," she said. "My hope is that one day soon we can come together and find solutions to the very important issues facing our nation rather than continuing to hurt one another."