GRAETTINGER, Iowa (AP) — The Latest on the fiery derailment of a freight train in northwest Iowa (all times local):

5:40 p.m.

The Palo Alto County Sheriff's Office says residents of three households that were evacuated near the site of a train derailment and fire in northwest Iowa have been allowed to return home.

The department says the three homes were each at least a half-mile from the site, where the ethanol-fueled fire was still burning late Friday afternoon.

The derailment occurred around 1 a.m. Friday near Graettinger (GREHT'-ihn-jur), about 160 miles northwest of Des Moines. It sent 27 tanker cars, each carrying 25,000 gallons of ethanol, off the tracks. The sheriff's office says two crew members escaped unharmed. No injuries had been reported by Friday evening.

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3:45 p.m.

An Iowa Department of Natural Resources official says fire from the derailment of a train shipping ethanol through northwestern Iowa was still burning nearly 15 hours after it began.

Field office supervisor Ken Hessenius (Heh-SEHN'-ee-uhs) said Friday afternoon that "there was a pretty big explosion" around 2:30 p.m. at the site near Graettinger (GREHT'-ihn-jur). Hessenius said he officials expected the fire to have burned out by Saturday, allowing investigators and railroad crews to better assess the damage then.

He says it did not appear any significant amounts of ethanol had spilled into a creek at the derailment site after staff from his agency checked downstream. Hessenius says a water sample from the creek hadn't yet been lab tested, but said the water appeared uncontaminated after "a smell test."

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2:15 p.m.

The National Transportation Safety Board says it's sending some of a 15-member investigative team from the site of a fatal train collision on the Mississippi coast to rural northwest Iowa to look into a derailment that caused an ethanol-fueled fire.

A news release Friday from the NTSB says some members of the team will be coming from Biloxi, Mississippi, where the agency is investigating a Tuesday crash in which a Texas tour bus was hit by a freight train at a crossing, killing four.

Other members of the investigative team heading to Iowa will come from NTSB headquarters in Washington.

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12:15 p.m.

Environmental experts are checking for ethanol leaks after a fiery freight train derailment in northwest Iowa, while fire officials are allowing the blaze to burn itself out.

The Palo Alto County Sheriff's Office says the derailment occurred 1 a.m. Friday, near Graettinger (GREHT'-ihn-jur).

Iowa Natural Resources field office supervisor Ken Hessenius (Heh-SEHN'-ee-uhs) says he doesn't yet know if any ethanol leaked from the 27 tanker cars that derailed. Each carries about 25,000 gallons.

County emergency manager Mark Hunefeld (HUH'-nee-fehld) says it appears that five of the derailed cars fell into a creek. The creek flows through relatively flat farm fields and empties a few miles downstream into the Des Moines River.

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10:20 a.m.

A spokeswoman for an ethanol producer says a train that derailed and burst into flames in northwestern Iowa was carrying ethanol from that company's plant.

Green Plains Inc. spokeswoman Sasha Forsen says the tank cars were filled with ethanol at a Green Plains plant in Superior, Iowa. She declined to say where the train was headed. Green Plains is based in Omaha, Nebraska.

The Palo Alto County Sheriff's Office says the derailment occurred 1 a.m. Friday, near Graettinger (GREHT'-ihn-jur), about 20 miles southeast of Superior. It says two crew members escaped unharmed. No injuries have been reported. Residents are evacuating the area.

Palo Alto County emergency management director Mark Hunefeld (HUH'-nee-fehld) says at least 27 of 101 cars derailed.

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9:50 a.m.

Authorities say several fuel tank cars are burning after a freight train, possibly carrying ethanol, derailed in northwestern Iowa.

The Palo Alto County Sheriff's Office says the derailment occurred 1 a.m. Friday, near Graettinger (GREHT'-ihn-jur), about 160 miles northwest of Des Moines. It says two crew members escaped unharmed. No injuries have been reported.

The office says the train was carrying alcohol from an ethanol plant. It didn't elaborate.

Palo Alto County emergency management director Mark Hunefeld (HUH'-nee-fehld) says at least 27 of 101 cars derailed, including the burning tanks that he believes were loaded with ethanol.

Residents are evacuating the area.

Company spokeswoman Raquel Espinoza has confirmed it's a Union Pacific train.

National Transportation Safety Board spokesman Keith Holloway says the agency will investigate the cause of the derailment.