Florida ? After goofing around in downtown Melbourne, four teenagers marched past a “no trespassing” sign and braved a railroad trestle that spans 200 feet over a creek. As they joked around and took pictures at the bridge’s halfway point, an oncoming train barreled down the tracks, its whistle howling alarm.

Onlookers yelled for the teens to run or jump into the slow-moving water 20 feet below, but only a young boy could sprint to safety. The three others, all girls, were killed Saturday as the sun set over Crane Creek, police and witnesses said.

The teenagers had been hanging out in Melbourne’s downtown area — known for its shops and nightclubs — when they decided to cross the trestle around 6:30 p.m., Lt. Curtis Barger said. Their parents had dropped them off at a mall, and then they took a bus downtown where they were “just goofing off,” he said, without elaborating.

The teens could have jumped onto an old, rusty trestle next to one they were on, though it was unclear why they didn’t.