The 15-year-old Prince George’s County boy critically injured after fights erupted at Six Flags America on Saturday night may have been the victim of a brawl partly organized by teens on Twitter.

The boy, who was punched in the head several times and is in a coma, was expected to have surgery Monday to reduce swelling, but the procedure was postponed, a family representative said. Meanwhile, authorities said they are investigating reports that teens using social media hours before the incident began communicating that there were plans to turn the annual Halloween-themed celebration called Fright Fest into “Fight Fest.”

“I hope nobody don’t fight at six flags, but I already gotta feeling they are,” read one tweet.

At 8:50 p.m., park visitors began calling 911, reporting several fights in the park and outside its gates. Throngs of teenagers lined the park’s perimeter on Central Avenue, witnesses said, as parents arrived to search for their children while patrons and park visitors poured out of Six Flags and filled the parking lot.

“It was panic, mayhem, chaos,” said Katrina Walker, who had dropped off her son and two of his friends at the park to celebrate his 15th birthday. “Everyone was fearful . . . parents were very scared because we had no idea if our children were hurt or if they got in the middle of something.”

Walker’s son left the amusement park safely. But family members said the injured teen, a DuVal High School freshman whose skull was fractured, had to be placed in an isolation area to prevent brain stimulation that could further complicate his injuries. “His life is lying in the balance as a result of someone randomly hitting him,” said Zina Pierre, a family friend. “He was hit blindly by the perpetrators and he was staggering, trying to get up, and some else came along to finish the deed.”

Police said the youth is expected to survive. Two other teens were treated by emergency medical crews. One was hospitalized with undisclosed injuries, Prince George’s County officials said. A third was released to her mother Saturday night.

Margo Hodge, a former nursing student and Navy veteran from Stafford County, was at Six Flags with her husband Saturday night. The couple left the park with their children at about 8:30 p.m. when they witnessed a fight and her husband saw someone with a knife, she said.

“There were literally mobs of 20 to 30 kids per group and there was just constant fighting,” Hodge said about the scene inside the park. “There was a handful of security officers, but they had no control of the situation.”

As Hodge’s family left the park, she said she saw dozens of teenagers coming toward the car, removing their shirts and yelling obscenities, racial slurs and the word “purge.”

Then she saw a boy who was not the DuVal student fall facedown in the crowd. She rushed over to help. When she flipped the boy over, he was bloody, bruised and missing his front teeth, she said.

Prince George’s police have not made any arrests connected to the incident but authorities are examining Twitter and Facebook posts to determine what might have sparked the fights, said Maj. Major Raphael Grant, commander of the Regional Investigation Division.

Grant said police also have heard concerns that some park visitors may have been playing a game or planned the night’s violence in advance, but authorities are still investigating.

“We haven’t eliminated anything,” Grant said.

Grant said he did not have an exact count of the fights that erupted during Fright Fest.

But Walker said her son and his two friends observed more than 10 fights, “and then they lost count.”

Dianne McNair, Walker’s mother, said that as she was looking for her grandson, swarms of young people were fighting on a grassy mound outside the park. As soon as one swarm was broken up by police, a new swarm formed and the fighting resumed.

“It was popping up in so many places like a firestorm,” said McNair, who saw one girl on the ground.

Six Flags officials described the fighting as an “isolated incident.” A spokeswoman said the amusement park does not plan to cancel Fright Fest, which is scheduled to run every weekend through Nov. 2.

“The safety and security of our guests is always our number one priority,” said a statement from Six Flags America spokeswoman Havilah R. Ross. “Steps are being taken to increase security by working closely with local law enforcement; increasing the number of dedicated security personnel within the park, in the parking lot as well as along Central Avenue; and continuing to enforce a zero tolerance policy for anyone violating our published code of conduct.”

Pierre said the fights that erupted Saturday were troubling, especially because the 15-year-old had gone to the park with his girlfriend and others for a simple night of fun.

“He should be in school today,” Pierre said. “He shouldn’t be in the hospital.”

Arelis R. Hernández contributed to this report.