"You could feel it in the environment," he said. "That negative feeling that something bad was going on."

Tensions also are high at Patterson Park High School, which has a large Latino student population, and Friendship Academy of Math, Science and Technology, Casa officials said.

Other racially tinged incidents have happened in the city in recent years. Last summer, a Hispanic man was beaten by a group of black teens near Patterson Park. A witness told The Baltimore Sun and a police dispatcher that one of the attackers said the man was targeted "because he's Mexican."

Over less than two months in 2010, five Latinos were shot or beaten to death. In one case, police said a 51-year-old Honduran man was attacked by a mentally troubled man who said he didn't like "Mexicans."

The attacks became a flash point for the city, exposing some of Baltimore's underlying racial fissures. Latino leaders worried that Latinos who are in the country without proper documentation didn't report crimes for fear they would be questioned about their immigration status.

In 2012, Mayor Stephanie Rawlings-Blake issued an executive order prohibiting Baltimore employees, including police, from inquiring about immigration status in the course of city business. She said she hoped the order would encourage more Hispanic immigrants to move to Baltimore and boost the city's tax base and population.

On Monday, Rawlings-Blake voiced her disappointment about recent events.

"There is simply no place in our city for violence, especially not in our schools — where we send our children to learn and grow," she said in a statement. "As the mother of a young child, it absolutely breaks my heart to hear of any incident that involves youth as either the victim or perpetrator of crime.

"Making Baltimore a safer city is my administration's top priority and I remain committed to doing all I can to make sure our youth have the necessary resources to rise above senseless violence."

On Monday, Casa and other organizations launched a social media "onebmore" hashtag campaign to raise awareness. "Stop Hatin' No Mas! It's time to come together as #onebmore to support our youth & provide a safe space to learn & thrive!" one participating group tweeted.

Members of civil rights organizations said they plan to recruit black youths across the city, teach them about cultural differences and send them to work with Latino groups on various projects and to help foster an environment of tolerance and understanding.

"If they're different from you, you need not hate," Baltimore NAACP branch president Tessa Hill-Aston said.

The Rev. Cortly "C.D." Witherspoon, president of the Baltimore chapter of the Southern Christian Leadership Conference, said he would like African- American and Latino leaders to begin meeting regularly during "Black and Brown" dinners to address social issues together — and set an example for young people.

As the news conference closed on Monday, black and Hispanic leaders all linked hands during a prayer as a show of solidarity.

"It's a sad state we are in," said J. Howard Henderson of the Greater Baltimore Urban League. "We should not have students of any race afraid to attend Baltimore City schools."

Baltimore Sun reporters Erica L. Green and Justin Fenton contributed to this article.