A freight train derailed Sunday afternoon in downtown Pittsburgh with massive freight cars and debris landing less than 100 feet from a light-rail and bus station where passengers were waiting for their bus or train.

Several cars landed on the track used by the light-rail train. A light-rail train had passed through the area just a few minutes before the accident. A fast-thinking Port Authority employee who was working the ticket booth at the time quickly directed passengers from both platforms and away from the accident.

Public safety officials said that no one was hurt and none of the cars was carrying hazardous or flammable chemicals. The route is often used by trains pulling oil tankers, natural gas and chemicals used in the fracking of natural gas.

The freight train was traveling west along the Norfolk and Southern Railway line near Station Square when the cars fell off the track around 1 p.m. A spokesperson for the railway said that crews that specialize in removing and cleaning up from train derailments were en route for Pittsburgh. A special crane capable of lifting the loaded cars off the hill would have to be brought in as well.

On Monday morning, crews could be seen working to stabilize the fallen cars and beginning the removal process. Several cars could be seen dangling and a large crane was being used as a brace to keep the cars from rolling further down the hill.

Over 26,000 people use the light-rail service each day to get into and out of the city for work.

“I was two hours late for work this morning,” said Rachel, who works in a downtown law office. “My boss was pretty cool about it, but I don’t know how long that will last. I ended up driving, but parking cost me $14 and I only make $11 an hour.”

The freight train was 7,687 feet long, or just short of a mile and a half. It weighed 4,838 tons and had three locomotives. The train was made up of what are called well cars, which are used to carry containers from ships or trucks. It was headed west to Chicago from a railyard in New Jersey. Scores of other trains have been backed up, sidelined or re-routed as a result.

It’s hard to describe the complicated topography of the area. The rail line where the derailment occurred runs parallel to the Monongahela River part way up the slope of what is called Mt. Washington. The track is dug into the side of the hill and runs along the length of it, gently rising.

At the base of the slope runs the transit line used for light-rail commuter trains running into and out of the city before turning into a tunnel going under Mt. Washington. Further up the slope runs a roadway used by cars and trucks going to the top of Mt. Washington.

No explanation has been given for the cause of the accident, but railroad officials were quick to rule out a rock slide, without giving any reason. Early this year a mudslide closed the roadway above the track for a number of days as crews removed debris from the road and secured the hillside.

There have been several mudslides so far this year in the Pittsburgh area, including one that destroyed a major route out of the city to the east and another that destroyed roads and homes in the city’s west end.

Even if mud and rock didn’t fall onto the track, if the ground underneath the track shifted it could have weakened the outer rail, causing the train to tip. The well cars were double-stacked with containers, adding to the weight and torque of the cars, a practice that has become common to cut transport costs and boost profits.

Railroad officials estimate the cleanup could take through Wednesday and possibly longer.

Port Authority officials which operate the light-rail trains have not been able to estimate when service will be restored as they have to wait for the freight cars to be removed before they can inspect the track for damage.

The accident only underscores huge problems in the region’s infrastructure which are reaching a crisis point. A study of the region’s many bridges found that nearly one third are structurally deficient. Many were built more than 100 years ago. In the past year there have been four water boil advisories for Pittsburgh residents because of water contamination caused by broken pipes, and the city has one of the highest percentages of lead used in water pipes with no plan to replace them.