Australian police have launched a criminal investigation into the docking and disembarking of passengers from the Ruby Princess cruise ship in Sydney last month, which led to Australia's highest concentration of coronavirus cases.

Authorities have been criticized for allowing 2,700 passengers and crew to disembark from the ship when it docked in Sydney on March 19.

A total of 11 of the ship's passengers have died, with four of the deaths over the weekend.

New South Wales Police Commissioner Mick Fuller said in a statement Sunday that the investigation will look at the actions of all parties involved, including government agencies and cruise line officials.

"This is a complex issue and we will need information from many witnesses to answer all the questions about how this ship ended up docking last month,” he said. “We are mindful that some of the key information we need will also come from passengers, so I urge those who were on-board to reach out to us."

Authorities in Australia have confirmed 342 cases of COVID-19 in passengers who got infected while on the ship or before boarding.

Not all crew members disembarked, and an unknown number are ill. Princess Cruises posted a message on its website March 30 as the ship floated off Australia's coast.

"Being able to send home those crew members who are not required for the safe operation of the ship is the right thing to do both from a humanitarian point of view and Australia’s international standing as a maritime nation that looks after foreign nationals in its care," the post reads. "We remain concerned that it is not safe for the ship to sail away from Australia while there are crew members on board who are ill."

Princess Cruises has been at the eye of the coronavirus storm with two of its ships, the Diamond Princess and the Grand Princess, experiencing significant, back-to-back outbreaks of COVID-19 in the span of two months.

In February, more than 700 people tested positive and 11 died after being on board the Diamond Princess, which was quarantined for two weeks off the coast of Japan.

At least 103 Grand Princess passengers were infected and two have died; that ship docked in Oakland, California, last month. U.S. passengers from both ships were quarantined at military bases for two weeks after returning.

Disembarkation began Saturday for passengers on the Coral Princess, hours after the ship docked in Miami with at least a dozen people on board who have tested positive for the novel coronavirus.

A representative for Australia's Department of Foreign Affairs and Trade (their counterpart to the U.S. State Department) confirmed that 80 Australian citizens left the ship Saturday.

"All of us at Princess Cruises are deeply saddened to report that two guests passed away on Coral Princess," the company said in a statement shared Saturday by spokesperson Negin Kamali. "Our hearts go out to their family, friends, and all who are impacted by this loss. All of us at Princess Cruises offer our sincere condolences."

Their causes of death were not disclosed.

Disembarkation of the Coral Princess at Port Miami is expected to span several days. The first to disembark will be those who need medical care.

Passengers who are healthy and fit to fly are expected to begin disembarking Sunday, the line announced in a release shared Saturday by Kamali. They will be transferred directly from the ship to Miami International Airport for flights home.

Passengers who are exhibiting any signs of respiratory illness or who are recovering from being ill will be kept on board until they're cleared by the ship's medical personnel.

As of Thursday, seven passengers and five crew members had tested positive for COVID-19, the novel virus that has infected more than 1 million people worldwide and killed more than 60,000.

There are 1,898 people on board, including 1,020 passengers and 878 crew members.

The cruise ship had been working to dock April 6 in Fort Lauderdale, Florida, where two Holland America ships, the MS Rotterdam and MS Zaandam, docked Thursday. Between those two ships, more than 200 people had reported coronavirus-like symptoms, and 14 critically ill people were taken to Florida hospitals, and the Coral Princess went to Port Miami instead.

More:Coronavirus travel restrictions around the world: A country-by-country list

The Coast Guard said in a news release Saturday it has been involved with processing about 120 vessels carrying some 250,000 passengers over the past three weeks because of the coronavirus pandemic.

The Coast Guard statement said as of Saturday there are 114 cruise ships, carrying 93,000 crew members, either in or near U.S. ports and waters. That includes 73 cruise ships, with 52,000 crew members, moored or anchored in U.S. ports and anchorages. Another 41 cruise ships, with 41,000 crew members, are underway and close to the U.S.

Contributing: Morgan Hines, USA TODAY; The Associated Press