SOUTH BEND, Ind. — Those looking for an answer as to why an Amtrak Train carrying around 170 people derailed Sunday morning in Niles will have to exercise a little patience.

Investigators say it could take between six months to a year and a half before a full report on the derailment is complete.

“It really depends on the complexity of the accident and can vary,” said Mike Flanigon, lead investigator with National Transportation Safety Board, at a press conference Monday morning at Staybridge Suites in South Bend, Ind.

Flanigon declined to speculate as to what caused the derailment, which left at least 10 people injured. All but one of the injured persons have been released from the hospital.

“Those are the sorts of numbers that are likely to change over the next couple days as we get more information,” Flanigon said.

Right now, investigators from the NTSB, Amtrak and the Federal Railroad Administration are in the beginning stages of determining why Amtrak Wolverine Service Train 350 derailed about two miles east of Niles, near Renaissance Road in the Niles Industrial Park shortly after 10 a.m. Sunday. Initial reports said the train was carrying about 170 passengers and crew, traveling from Chicago to Pontiac.

Flanigon said all of the train’s four cars and two locomotives derailed on a yard track.

Investigators began inspecting the tracks and the signal system last night. Today, investigators will perform a standing test of the train’s brake system. Flanigon said they would also interview Amtrak crew, maintenance personnel and the train dispatcher in Chicago.

Flanigon said it could take between four days to a week to conclude the initial fact-gathering portion of the investigation.

“That is typical, but we are here until the job is done,” he said. “Our goal is to collect the perishable evidence, interview people who need to be interviewed and then collect paper data, electronic data and take that back to Washington with us.

“We really don’t speculate at this stage or any stage. This is a fact-gathering investigation at this point and we don’t want to limit ourselves. We are looing at everything.”

The derailed train has been put back on the tracks so investigators can perform a brake test today, Flanigon said.

Officials from Amtrak said today all services to and from Michigan are in operation.