Officials are still trying to determine what caused a Brooklyn-bound F train to derail in Woodside, Queens earlier today. At a press conference this afternoon, Deputy Chief James Leonard announced there were 19 injuries due to the derailment, including four serious ones; approximately 1,000 people were rescued from the eight-car train after the derailment. You can see some up close photos of the rescue from inside the tunnels above.

The train derailed about 1,200 feet south of the 65th Street local station while running on the express track. According to the News, the derailment happened in an area where there is a long and sweeping curve that trains enter after a downhill run; the curve has a speed limit of 35 miles-per-hour.

Officials haven't given any indication as to why it derailed there: "We are focusing on investing the problem," MTA CEO Thomas F. Prendergast assured reporters. The last subway derailment came on May 29th, 2013 when a 1 train derailed just south of 125th Street in Manhattan; you can see a brief timeline of past derailments here.

Passenger Mark Udit, 31, told us he was in the front car when the lights suddenly went off. He said that it didn't feel like the train derailed, but rather like a "severe but regular jolt, as if the car has hit a bump." The conductor came on and told passengers the train had derailed and it would take a while to get out. Udit said he had to wait approximately ninety minutes to get off.

Initially, police and FDNY officials planned to send rescue trains to pick up passengers, but that plan was scuttled. Instead, emergency workers led passengers through the tunnels to a ladder that led to a hatch on the sidewalk near 60th Street.

While the first car was mostly undamaged, Udit noticed that the third car was "on a good tilt," and there were a bunch of mangled seats. There was no ventilation in the tunnel, so many people felt dizzy and required oxygen. Six out of the eight train cars went off of the tracks—the only ones that didn't were the front and last cars.

"The train was shaking and the cars in the front started tilting to the right," passenger Melissa Delgado told the Post. "I heard a pang and then a screech and then the train came to a halt." "I thought it was an earthquake," passenger Caisha Jean Phillipe told the Wall Street Journal. "I thought it was driving too fast then the train just" stopped. "It was like really scary, we felt like it hit something," said fellow passenger Gabrielle Hesop. "We thought we crashed into a train, or we thought the train was on fire."

The MTA has been working all afternoon to put the cars back on the rails in order to move the train. Subway service on the E/F/M/R is expected to be running for rush hour, but officials warn that delays and overcrowding should be expected. Check here for updated information about service delays.

Additional reporting by Douglas Capraro.