(CNN) -- Riding tons of falling concrete to the river bank below, dozens of children on a summer field trip survived the collapse of an interstate bridge in Minneapolis, Minnesota, during evening rush hour on Wednesday.
"We were on our way back from the swimming field trip," said Ryan Watkins, one of the youths on the bus.
"We were riding over the bridge and the bridge collapsed, and we were right on the part where it went down -- where it curved down," he said, describing the collapse of the Interstate 35W bridge near University Avenue.
Watkins was one of 52 children and nine adults who survived the accident, according to Tony Wagner, president of the local nonprofit social services group that organized the trip.
Eight of the kids, ages 5 to 14, were hospitalized with injuries, Wagner said.
"I know a little girl who was bleeding," Watkins said shortly after the accident. "I didn't see what happened, but she was bleeding in between her legs and another girl had hurt her neck."
Two adult staff members also were hospitalized, one with a back injury, Wagner said. Watch as driver describes helping kids from bus »
The bridge collapse killed at least four people and injured at least 62 others, officials said.
Images of the bridge collapse, which happened shortly after 6 p.m. (7 p.m. ET), showed vehicles -- many of them damaged -- hanging off parts of the bridge. Some had fallen into the Mississippi River below, which was littered with concrete chunks that broke off during the collapse. The bridge was separated from the land-based sections of the highway on its northern and southern ends. See photos of the aftermath »
Kristy Jenkins, the mother of one of the children on the bus, said that had it not been for the "quick thinking" of one of the staff members with the group "we might be experiencing something different right now."
Jenkins credits staff member Jeremy Hernandez with saving her 12-year-old daughter, Nina.
"I don't know what he was thinking," Jenkins said. "It must have been something really good." Watch as teen describes first rescue efforts
Nina said Hernandez "busted open the backdoor of the bus and he told everyone to get out from the back of the door. We jumped on the highway and then jumped on the sidewalk." Watch Hernandez describe how he handed kids out the bus door »
"It was scary, terrifying," she said. "There were a lot of people who got hurt."
Hernandez said he was just happy the kids were reunited with their parents and was "glad to be alive."
"If it would have been a second later, any second before, we would have been in the water or under the pavement, because the pavement crushed another car that was in front of us," he said.
Gary Babineau was driving a truck in front of the bus when the collapse occurred.
After recovering from his momentary shock, Babineau said he climbed out of his truck and rushed to help the kids in the school bus behind him.
"Most [of the kids] were crying pretty bad ... screaming, crying -- a couple of them were bleeding," he said, adding some looked like they were hurt.
"We were setting them down on the bridge and telling them to run," he said.
Babineau and others on the bridge picked up a few of the children and carried them to a safe distance.
"We didn't know at the time if they could walk, and we didn't want to chance it at the time that they might have a broken bone," he said. E-mail to a friend
CNN's Leslie Wiggins contributed to this report.
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