Federal crash investigators were due in New Orleans on Saturday morning to start working out how a 500-foot tanker veered across the Mississippi River and slammed into a paddle-wheel cruise boat tied up at the riverfront. The smaller boat rolled onto its side and sank beside the dock. Somehow every one of the roughly 180 passengers and crew members got out alive.

The crash happened at about 12:30 p.m. Friday just upriver of the Crescent City Connection bridge. The asphalt tanker Atlantic Asphalt was moving north to pick up cargo when it swung hard to the right and hit the American Heritage broadside. The riverboat, run by American Cruise Lines, had pulled in near the port headquarters about two hours earlier so guests could head home after an eight-day trip on the lower Mississippi.

Mayor Helena Moreno said 32 people went to hospitals, 30 passengers plus two harbor police officers. None of them had injuries considered critical. She called the result a miracle on the Mississippi. Gov. Jeff Landry used the same phrase and credited local, state and federal crews with saving many lives.

How the rescue unfolded

Passengers had already begun filing off when the boat started to lean. Harbor police said about 87 people stepped off while it was still afloat. Two officers and two firefighters climbed aboard as it listed, yet the vessel turned over before everyone reached the dock, tipping people into the chilly brown water. Video shot from shore showed some swimming away in orange life vests while others scrambled over the railings as the deck rose.

Tugboats, a police boat, a fireboat, Coast Guard crews and nearby workers fished people out. Police said it took 30 to 45 minutes to get the last of them onto boats. A restaurant manager on the riverboat said the tanker's bow punched a hole into the dining room. He said the crew drills for emergencies every week, so they stayed calm and steered frightened guests toward safety.

Capt. Brian Clesi of the Creole Queen, a sightseeing paddle-wheeler docked a quarter mile away, sped over in his boat's small rescue launch with second mate Ellis Kimball Jr. Many of the people in the river were older and too heavy to haul aboard. Kimball held them by the arms while Clesi ferried them to larger boats. The two men said they helped about nine people, starting with a harbor police officer clinging to the stern. Only two of them had life vests on.

Officials said no children were aboard and most passengers were visitors from out of state. The city helped them replace medicine, phones and other belongings lost to the river. The cruise line said it had moved everyone into hotels.

What investigators will look at

Coast Guard Capt. Melanie Burnham said the tanker appears to have had some kind of steering failure but stressed that the exact cause is still unknown. A veteran river pilot had boarded the tanker roughly half an hour before the crash, which is routine for foreign ships on this stretch of river.

The National Transportation Safety Board had a team ready to fly in Friday, but the nationwide flight shutdown that afternoon kept it on the ground. The board said its investigators expected to arrive Saturday. State engineers confirmed the tanker never touched the bridge before it hit the riverboat.

The Atlantic Asphalt flies the flag of the Marshall Islands. Ship tracking services list its owner as a company based in Liberia. It had reached New Orleans two days earlier after a stop in New Jersey. The American Heritage is a 295-foot paddle-wheeler built in 2015 that holds up to about 150 guests.

The Coast Guard closed a three-mile stretch of the river during the rescue and reopened it to ship traffic Friday night. Ferry service from Algiers Point resumed too. For longtime residents the scene recalled December 1996, when a freighter that lost control plowed into a wharf beside the Riverwalk mall and injured dozens.