The Boston fans cheered for the first responders and booed the Celtics.
Not long after a ceremony to honor the police, doctors and other Boston Marathon workers who helped those injured by a pair of bombs at the race's finish line, the crowd at the TD Garden turned against the hometown team when it quickly fell behind the New York Knicks.
The first boos were heard in the first half, when the Celtics trailed by as many as 18 points in Game 3 of their first-round playoff series against New York. By the time Boston skulked off the court with a 90-76 loss, the only cheers in the half-empty building were from the fans in Knicks orange and blue.
"We've just got to be mentally tougher," Celtics coach Doc Rivers said. "And I didn't think we were tonight. I just thought we fought for a little while (and) kind of gave in."
Celtics stars Kevin Garnet and Paul Pierce hid in a back room for more than an hour after the game before emerging.
"I thought there was a lot of energy in the building," Pierce said. "You want it so bad and you rush, and get real anxious. And I thought that's what we did tonight."
Rivers said he didn't know what to say to his team yet to get them to respond after falling behind 3-0 in the best-of-seven series.
"It's a simple message: You've got to win the next one," he said. "It's simple. And that's where it starts."
The Celtics need to win Game 4 to avoid their first playoff sweep since 2004. No NBA team has ever come back from a 3-0 deficit to win a best-of-seven series.
"They haven't won it yet," said Jeff Green, who had 21 points and nine rebounds. "As long as we're still playing, we have a chance. It's a new game — Game 4. We just have to leave it all on the floor."
In their first game at home since the April 15 marathon bombing, the Celtics failed to get an emotional boost from a pregame ceremony honoring the victims and first-responders.
Rivers said he wasn't sure if his team was too hyped up at the start of the game.
"I don't know," he said. "I can't get into their heads."
An honor guard from the Boston police, fire and emergency medical services brought out the American flag, and a cappella group Voices of Freedom, in military uniforms, sang the "Star-Spangled Banner" before the game. The moment of silence was punctuated often by pro-Boston cheers.
"They've been through a lot," Rivers, whose father was a police officer in the Chicago area, said before the game. "I think they can't get enough support; they can't get enough love. So I think it will be wonderful for them and for the fans as well."
The Celtics were scheduled to play Indiana in Boston in their regular-season finale April 16, the day after the bombings. The game was canceled, and the Celtics began the playoffs in New York, where they went down 0-2 in the best-of-seven series.
The Bruins and Red Sox received an emotional welcome on their return, and Friday it was the Celtics' turn.
Between the first and second quarters, the time the Celtics traditionally recognize a "Hero Among Us," dozens of doctors and nurses, police and other law enforcement officials and marathon volunteers were given a standing ovation when they were escorted onto the court by Gov. Deval Patrick.
Fans at the game were subjected to increased security, including searches of their cars and metal-detecting wands. Once inside, they found white T-shirts on their seats with "Boston Strong" written in Celtics green.
The basket supports featured an ad for the One Fund, the charity established to help the bombing victims.