Some injuries children suffered in an Indianapolis school bus crash that killed the driver and a student could have been prevented if the bus had seat belts, a lawyer said Thursday.

Attorney Ken Nunn of Bloomington filed two lawsuits in Marion County court this week against Miller Transportation Inc., the company that owned the bus, on behalf of three families whose children were on it when it crashed.

An attorney for Miller Transportation didn't immediately return a phone call seeking comment.

Donasty Smith, 5, and Thomas Spencer II, 60, died in the March 12 crash when the bus carrying 50 children to Indianapolis Lighthouse Charter School collided with a concrete bridge pillar. Ten more students were injured.

The lawsuits claim Miller failed to provide a safe school bus. Nunn said Spencer was wearing a seatbelt when the bus crashed, but there were no seat belts for the children. Indiana does not require seat belts on school buses, although officials say some districts provide them.

Nunn said one of his clients broke his leg when he was hurled out of his seat and slid beneath several rows of seats.

"If he had remained in his seat, he wouldn't have been hurt," Nunn said. He added, "Those kids became human missiles."

Three of the five children Nunn represents, who he said were ages 9 to 14, have leg or ankle injuries, and four have post-traumatic stress, the lawsuits say.

They also claim the company was negligent because it was responsible for Spencer's actions and failed to properly train him or monitor his health. Investigators have said Spencer did not have any type of medical issue.

Nunn said he plans to file more lawsuits, including one against the state of Indiana for not requiring seat belts on school buses. He also plans to lobby legislators to pass a seat-belt law next year.

"The plan is to sue everybody I think was not using their noodle ... and investigate this further," Nunn said.

State Rep. Robert Behning, a Republican from Indianapolis who chairs the House Education Committee, didn't immediately return phone calls seeking comment Thursday.

But he said last week that the issue of school bus restraints may come up in the Legislature next year if media coverage continues or another accident occurs.

Nunn said having seat belts on school buses was "just common sense" because the devices are already required in cars and trucks. "They can tell us it's not required, but if it's not required, why don't they cut the seat belts out of their cars?" he said.

School buses are heavier than normal cars and distribute forces differently after crashes, so riders feel less of an impact. Buses also are designed so that the seats absorb some impact in a crash, protecting riders.

However, the National Transportation Safety Board website says the agency believes additional standards are needed to provide better protection for school bus passengers. Six states require large school buses to come equipped with seat belts.

Michael LaRocco, the state education department's director of school transportation, said last week it would cost about $160 million to equip all of Indiana's 16,000 school buses with effective restraints, and neither the state nor individual districts can afford that.

LaRocco wasn't available for additional comment Thursday.