BALTIMORE (AP) — The container ship that caused the deadly collapse of Baltimore’s Francis Scott Key Bridge was refloated at high tide Monday and began slowly moving back to port, guided by several tugboats.

The Dali had been grounded at the collapse site for weeks after it lost power and crashed into one of the bridge’s supporting columns on March 26, killing six construction workers and halting most maritime traffic through Baltimore’s busy port.

The ship appeared to start moving shortly after 6 a.m. as crews began maneuvering it out of the wreckage. It started and stopped a few times before slowly backing away from the collapse site.

With the hulking cargo ship removed from the mouth of Baltimore’s harbor, a newly opened void appeared in the city’s skyline. The altered waterscape also highlighted the progress made on the cleanup effort as crews have already removed hundreds of tons of mangled steel from the collapse site.

Officials said the Dali would move at about 1 mph on the roughly 2.5-mile (4-kilometer) trip back to port, a fraction of the speed it was traveling when it lost power and brought down the bridge. Pieces of the bridge’s steel trusses protruded from the ship’s bow, which remained covered in mangled concrete from the collapsed roadway.

Officials have said the Dali will likely remain in the port for a several weeks and undergo temporary repairs before being moved to a shipyard for more substantial repairs.

Crews began preparing the ship to be refloated about 18 hours before it started moving. That process included releasing anchors and pumping out over 1 million gallons of water that were keeping the ship grounded and stable during complex cleanup operations. Crews conducted a controlled demolition on May 13 to break down the largest remaining span of the collapsed bridge, which was draped across the Dali’s bow.

Dive teams also completed inspections of the site to confirm there were no obstructions that would hinder the voyage.

Maryland Gov. Wes Moore, who observed the refloating process from the water, has scheduled a press conference for Monday afternoon to discuss ongoing cleanup and recovery efforts.

The Dali experienced two electrical blackouts within about 10 hours before leaving the Port of Baltimore on its way to Sri Lanka, according to a preliminary report released last week by the National Transportation Safety Board. The ship experienced two more blackouts as it was approaching the Key Bridge. Those failures caused it to lose propulsion and veer off course at the exact wrong time.

The FBI also launched a criminal investigation into the circumstances leading up to the crash.

The ship’s crew members haven’t been allowed to leave the 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.

Officials have said they will be able to disembark once the Dali is docked in Baltimore.

The bodies of six construction workers have been recovered from the underwater wreckage in recent weeks. All the victims were Latino immigrants who came to the U.S. for job opportunities. They were filling potholes on an overnight shift when the bridge was destroyed.

Officials plan to reopen the port’s 50-foot (15-meter) deep draft channel by the end of May. Until then, crews have established a temporary channel that’s slightly shallower.