VIDEO: Crews conduct controlled demolition of Baltimore bridge wreckage

Crews conducted a controlled demolition Monday to break down the largest remaining span of the collapsed Francis Scott Key Bridge in Baltimore.

BALTIMORE (AP) — Crews conducted a controlled demolition Monday to break down the largest remaining span of the collapsed Francis Scott Key Bridge in Baltimore.

The explosives flashed orange and let off plumes of black smoke upon detonation, and the span crumpled into the water in seconds. The longest trusses toppled away from the grounded Dali container ship and slid off its bow, sending a wall of water splashing back toward the ship.

It marked a major step in freeing the ship, which has been stuck amid the wreckage since it lost power and crashed into one of the bridge’s support columns shortly after leaving Baltimore on March 26. The demolished span came crashing down on the ship’s bow and remained resting on its deck for the past six weeks.

The collapse killed six construction workers and halted most maritime traffic through Baltimore’s busy port. The controlled demolition will allow the Dali to be refloated and restore traffic through the port as the cleanup enters its final stages.

Once the ship is removed, maritime traffic can begin returning to normal, which will provide relief for thousands of longshoremen, truckers and small business owners who have seen their jobs impacted by the closure.

Officials previously said the Dali’s 21-member crew would shelter in place aboard the ship while the explosives were detonated.

In a videographic released this week, authorities said engineers were using precision cuts to control how the trusses break down. They said the method allows for “surgical precision” and is one of the safest and most efficient ways to remove steel under a high level of tension.

The next step is for hydraulic grabbers to lift the resulting sections of steel onto barges.

The Dali crew members haven’t been allowed to leave the grounded vessel since the disaster. Officials said they’ve been busy maintaining the ship and assisting investigators. Of the crew members, 20 are from India and one is Sri Lankan.

The National Transportation Safety Board and the FBI are conducting investigations into the bridge collapse.

Danish shipping giant Maersk had chartered the Dali for a planned trip from Baltimore to Sri Lanka, but the ship didn’t get far. Its crew sent a mayday call saying they had lost power and had no control of the steering system. Minutes later, the ship rammed into the bridge.

Officials have said the safety board investigation will focus on the ship’s electrical system.