BRIDGEPORT, Conn. - Thousands of Connecticut commuters should brace for travel chaos on Monday as Metro-North workers repair damage on the United States' busiest rail line caused by the collision of two trains, officials warned on Sunday.

Lengthy detours and hours of traffic backups were likely as many daily train commuters take to the road, officials said. The Friday derailment of a Metro-North passenger train that struck a commuter train between Fairfield and Bridgeport, Connecticut, injured more than 70 people and halted full service on the line indefinitely.

The Monday commute will be "extremely challenging and I am activating the state's Emergency Management System. There will be serious disruptions all week, and I would encourage anyone who can, to stay home, if possible," Governor Dannel Malloy told a news conference.

The Connecticut Department of Transportation was preparing a plan to accommodate commuters. The agency, as well as Malloy and US Senator Richard Blumenthal, urged people through the news conference to make alternate plans and suggested that they stay home if they could.

Malloy said that 30,000 daily commuters will be seriously affected on Monday and likely the entire week.

The site of the crash is about 50 miles (80 km) northeast of New York, and Metro-North train service between New Haven and South Norwalk is indefinitely suspended.

Service by Amtrak, the US passenger rail service, is also indefinitely suspended. Officials reiterated on Sunday that they do not know when service would be restored.

The New York-New Haven line is the busiest rail line in the country, serving 125,000 commuters a day, said Judd Everhart, a spokesman for the Connecticut Department of Transportation.

Regular service will run from the Stamford station and South Norwalk station to Grand Central Terminal in New York. Limited service will run from Westport.

The state Department of Transportation said that during the morning commuter train service would run every 20 minutes from New Haven to Bridgeport on the New Haven commuter line.

Two buses will run from Bridgeport to Stamford Station bypassing the site of the accident.

Regular service will run from Stamford station and South Norwalk station to Grand Central Terminal. Limited service will run from Westport station.

Earl Weener, a board member for the National Transportation Safety Board (NTSB), told the news conference the agency was finishing its probe of the crash site and would turn it over to Metro-North on Sunday.

All the train cars had been removed, recording devices had been recovered and crews were being interviewed, he said.

Weener said hundreds of pounds of track had been sent to the NTSB laboratory in Washington. The track includes a section of fractured rail that may have caused the accident or been caused by it.

State transportation officials said that more than 2,000 feet (600 meters) of track must be repaired and replaced.

Of the more than 70 passengers and crew members injured, eight remained hospitalized on Sunday. Three were in critical condition, officials said.

PROBE NEARLY OVER, 'NIGHTMARE' JUST STARTING ? ?

While the on-site federal probe is nearly over into the cause of a collision by two Metro North commuter trains Friday night between Fairfield and Bridgeport when one of the trains derailed, the "nightmare and chaos" for commuters will only begin during Monday morning's rush hour, local, state and federal officials said Sunday.

Officials are predicting potential chaos, including detours and hours of traffic backups as many daily train commuters take to the road.

Even as DOT officials were preparing a plan to accommodate commuters, the state agency, as well as Connecticut Gov. Dannel P. Malloy and US Sen. Richard Blumenthal were warning people to make alternate plans and suggested that people stay home if they can.

Fairfield police warned on its Facebook page Sunday that "Commuters need to be prepared for a long commute on Monday. Please make alternate plans and please consider staying home if possible."

"I'm really in the same boat as everyone else, as I plan to head down to Washington to make it clear to the White House that I am deeply concerned about our nation's railway infrastructure," said Blumenthal, after a press brief Sunday in Bridgeport held by the National Transportation Safety Board.

"This accident shows that safety cannot be compromised, and is going to cost tens of millions, if not hundreds of millions of dollars in lost revenue. We need to find the problems before they lead to accidents like this one."

Meanwhile, Metro-North train service between New Haven and South Norwalk is indefinitely suspended, as well as Amtrak service between New York and New Haven, because trains cannot go through the crash site. Officials reiterated Sunday that they do not know when service will be restored.

Regular service will run from the Stamford station and South Norwalk station to Grand Central Terminal. Limited service will run from Westport station.

DOT plans include providing shuttle buses from New Haven to Bridgeport along the New Haven commuter line, and that during the morning commute train service will run every 20 minutes at Fairfield Metro, Fairfield and Westport Stations - bypassing the site of the accident.

Earl Weener, a board member for the National Transportation Safety Board, told the news conference the agency was finishing its probe of the crash site and would turn it over to Metro-North on Sunday.

All the train cars had been removed, recording devices had been recovered and crews were being interviewed, he said.

"But it will take a significant amount of time to repair the tracks," he said.

Weener said Sunday that "hundreds of pounds" of track that includes a section of fractured rail that may have caused the accident or been caused by it, has been sent to the NTSB Lab in Washington for analysis.