(Adds update from sheriff's office)
By Jarrett Renshaw
NEW YORK, March 10 (Reuters) - More than two dozen tank cars hauling ethanol derailed Friday morning in northwestern Iowa, causing some to catch fire and sending an unknown volume of the biofuel into a nearby creek, officials said.
There were no reported injuries, according to the U.S. National Transportation Safety Board, which is sending a 15-member team to Iowa to investigate.
Nearby residents who were asked to evacuate earlier in the day have returned to their homes, the Palo Alto County Sheriff's Office said in a statement.
The derailment occurred around 1 a.m. (0700 GMT), on a Union Pacific Corp rail line near Graettinger and along Jake Creek, about 160 miles northwest of Des Moines, the NTSB said in a press release.
Flames were still visible at the derailment site at 10:30 a.m., and that was expected to continue for several more hours as emergency officials let the fuel burn off, the sheriff's office said.
Local officials from the Iowa Department of Natural Resources collected water samples from the creek for testing, the sheriff's office said.
The NTSB said the train included three locomotives and 101 cars, 100 of which were carrying ethanol, an ingredient in U.S. gasoline. The tank cars were DOT 111 models, which the NTSB has long criticized as puncture-prone and unfit for U.S. rails.
U.S. regulators have given ethanol shippers until 2023 to remove DOT 111s from the rails. Crude oil shippers were given a much shorter timeline.
The train left Green Plains Inc's Superior, Iowa, facility, a company spokesperson said. (Reporting by Jarrett Renshaw; Editing by Andrew Hay and Frances Kerry)