U.S. National Transportation Safety Board chair Jennifer Homendy said at a Senate hearing Wednesday that investigators had conducted interviews with key cargo ship personnel in the investigation of the March 26 Baltimore bridge collapse.

The Dali cargo ship crashed into the Francis Scott Key Bridge on March 26, sending it crashing into the harbor and killing six people. Work to clear the wreckage and restore traffic through the Mid-Atlantic state’s shipping channel is ongoing.

Homendy said investigators remained on site and had interviewed the pilots, the second officer – who was the man on watch at the time of the crash – and other key personnel, as well as U.S. Coast Guard personnel.

The NTSB has downloaded the voyage data recorder and brought the manufacturer of equipment in the engine room “to look closely at the electrical power system work.” The NTSB is also looking at the circuit breakers and has tested the fuel onboard the ship.

NTSB investigators are looking at the original bridge design and how it would be built today. Homendy said the preliminary report would be out the first week of May. “We are still on scene collecting information. We have a lot of work ahead,” she said.

The top Republican on the Senate Commerce Committee said at the hearing that Congress should help fund the replacement of the Maryland bridge.

“I think the federal government needs to help to rebuild the bridge,” Senator Ted Cruz said. “With court cases likely taking years to resolve, it’s also sensible for federal taxpayers to front the money now with legal protections so taxpayers are paid back by the legally.”

Source: Reuters reported by David Shepardson and edited by Franklin Paul and Mark Potter