Three more people are now behind bars in connection with an attack on a MARTA train more than a week ago.

MARTA police Chief Wanda Dunham told Channel 2’s Erin Coleman that they’ve arrested a 16-year-old, 14-year-old and 12-year-old.

The latest arrests bring the total number of people in custody to six. Detectives are still looking for a seventh person, 19-year-old David George Watkins. He should be considered dangerous, police said.

“I know we received a lot of criticism for remaining silent on this incident, but we have to remain in fact, not fiction,” Dunham said.

On April 16, police said a large group of teens and preteens boarded a southbound train at the Garnett station. According to a police report, they beat up two Delta Air Lines employees.

A man who witnessed the attack recounted the incident in an exclusive interview with Channel 2’s Erica Byfield.

“The next thing you know, they started just beating him. There was blood everywhere. People were hollering and screaming,” he said.

A week and a half earlier, a man robbed a bus full of passengers along Campbelton Road. Both incidents prompted a MARTA committee, on Tuesday, to recommend putting an extra $2.5 million into security. If approved, Dunham said they would add surveillance cameras to buses, trains and add more officers on patrol.

“It would represent a 60 percent increase in officers on our trains at night,” Dunham said. “A 100 percent increase in officers on buses.”

The $2.5 million is part of the 2012 fiscal budget which starts July 1.

A public hearing is scheduled for May 16 and 17, followed by final board approval. Dunham said after that, security upgrades would happen almost immediately.