Amtrak Downeaster train service between Boston and Portland was delayed for hours Sunday after South Portland police were notified that a rail car at the city’s Rigby Yard, near the Cash Corner and Thornton Heights neighborhoods, had a suspicious package attached to it.

South Portland police said in a Facebook post Sunday evening that the package was attached to a rail car parked near another rail car that contained hazardous materials.

That discovery by railroad employees led to a police order halting all train traffic traveling through Rigby Yard, a crucial link in Amtrak Downeaster Service between Boston, Portland and Brunswick. The incident was reported to police at 12:46 p.m.

“An abundance of caution was used to determine that the package was harmless,” Lt. Thomas Simonds said in the statement on Facebook. “Because the item was in close proximity to several rail cars marked as containing hazardous materials, it was deemed prudent to bring in extra assistance from the South Portland Fire Department and the Portland Police Department Explosive Ordnance Unit (the police bomb squad).”

Simonds said the rail car with the suspicious package was located near the southwest end of Rigby Yard at the farthest distance from Main Street businesses and neighborhoods. South Portland police determined that it would not be necessary to evacuate the area.

After examining the package, police determined that the item was a bag of personal goods, likely left behind by someone who was trespassing on railroad property.

Simonds said police secured the scene at 4:30 p.m. and all rail traffic was authorized to return to normal operations and schedules.

The delays had a significant impact on rail travelers, according to Patricia Quinn, executive director of the Northern New England Passenger Rail Authority.

Quinn said in an email Sunday night that Amtrak attempted to hire buses to keep train travelers moving, but there was a cruise ship in Portland on Sunday that interfered with that effort. Quinn said Amtrak wasn’t able to secure buses until late Sunday afternoon. It could not be determined how many Amtrak Downeaster riders were affected by the travel delays. Quinn said that all trains were moving and trying to get caught up with service as of 4:30 p.m.

Several agencies responded to the report of a suspicious package on a railroad car, including the South Portland Fire Department. Capt. Robb Couture, a fire department spokesman, said firefighters responded to the Rigby Yard around 1:30 p.m.

Railroad police also were called in to help with the investigation.