Authorities are piecing together what happened when a Mexican navy ship struck the Brooklyn Bridge, killing two people, over the weekend.
Marine experts have said the tide and water conditions in the narrow passage were to blame, while the mayor of New York and police have argued the captain of the ship lost control due to mechanical issues.
Meanwhile, in a statement distributed to US media, a spokesperson for the city's Office of Emergency Management said the Cuauhtemoc was headed in the wrong direction and it never intended to sail under the bridge.
Here's what we know.
What happened?
Onlookers were horrified as they saw the navy training ship crash into the bridge.
The vessel collided with the underside of the bridge and the mast snapped away as it drifted toward the promenade, where footage shows onlookers fleeing as it inched closer.
Sailors could also be seen on the rigging of the damaged mast but no-one fell into the water, authorities said.
Nineteen people were injured in the collision.
One of the victims was 20-year-old cadet America Yamilet Sanchez, who fell from one of the ship's masts, the Associated Press confirmed.
Videos show heavy traffic on the water at 8:20pm, about the time of the incident.
Mexican President Claudia Sheinbaum expressed regret at the loss of the two crew members.
"Our solidarity and support go out to their families," Ms Sheinbaum said on social media platform X.
The ship was on a promotional tour and was destined for Iceland.
Why did it happen?
The causes of the crash are yet to be confirmed but the National Transportation Safety Board is investigating.
New York Police Department Special Operations Chief Wilson Aramboles said an initial report suggested the pilot of the ship lost power due to a mechanical problem, though officials cautioned that information was preliminary.
At the time of the crash, the ship was moving through turbulent waters.
The tide had just turned and a fast current was heading up the East River as wind set in.
In the heavily trafficked New York Harbour, narrow channels, strong winds, and whirlpool eddies — circular currents that move against the flow — all contribute to a challenging passage.
Sal Mercogliano, a former merchant mariner who has powered multiple ships through the harbour, told the Associated Press all those "worst-case scenarios" — the ship's height, a strong current, heavy wind and the absence of a more controlled tugboat escort — all contributed to the tragedy.
"The prudent thing would've been to leave two hours earlier, when the tide was going out. That would've been the ideal time," said Mr Mercogliano, who writes a widely followed shipping blog.
"But I don't think they ever envisioned that their engine would've propelled them into the bridge."
Videos show a tugboat was close to the Cuauhtemoc at the time of the crash.
Tracking data from Marine Traffic and eyewitness videos show that the tugboat, the Charles D. McAllister, gently nudged the vessel as it backed astern into the channel but dropped off before the vessel turned.
Seconds later, as the ship continued drifting in the wrong direction, the tugboat tried to overtake the vessel but arrived too late to wedge itself between the fast-moving ship and the Brooklyn riverbank.
McAllister Towing, the company that would have operated the tug and been responsible for any docking pilot aboard, declined to comment.
Following last year's crash in Baltimore, Mr Mercogliano said port authorities there tightened rules to require a tug escort and slower speeds for vessels sailing through the harbour entrance past the partially collapsed Francis Scott Key Bridge.
But the ship that caused that collision, the Dali, was 50 times heavier than the Cuauhtemoc.
What will be investigated?
Mr Mercogliano said investigators would evaluate whether the Mexican crew performed the recommended safety checks prior to their departure.
Typically, that involves testing the engine's propellers, rudder and propulsion six to 12 hours in advance to make sure everything is working properly and nothing is left to chance.
"It's not like your car where you're just throwing your shifter," he said.
What happened to the bridge?
The 142-year-old Brooklyn Bridge did not suffer serious damage.
Cargo and modern warships generally avoid the area due to the low height of the bridges in New York Harbour.
This is not the first time, however, that a ship has crashed into the Brooklyn Bridge.
According to The New York Times, in 1921, the Edward J. Lawrence struck the bridge as the schooner was being towed beneath the central span.
Some 10 years later, a freighter struck a steel beam on the bridge, damaging three of the ship's masts.
The captain blamed what he characterised as an abnormally high tide.
In 1986, a South Korean freight ship scraped the underside of the bridge, destroying one of the ship's radars.
Where is the Cuauhtemoc now?
The damaged ship was moored at Pier 35 in lower Manhattan and a stream of people, including investigators and crew, were seen disembarking the vessel.
The vessel is being assessed, and the coastguard has established a 46-metre safety zone around it.
A report from the National Transportation Safety Board could take months.
