SAN ANTONIO — Five train cars overturned outside of San Antonio, spilling about 1,000 gallons of sodium hydroxide and prompting a temporary evacuation, officials said.

Monica Ramos, Bexar County sheriff’s office spokeswoman, said the derailment happened around 4 p.m. Sunday in an industrial area southwest of the city.

Ramos said the sodium hydroxide didn’t cause fumes or residue. Two men inside a tug car that overturned suffered minor injuries and were treated on scene before being released. A nearby flea market was also temporarily evacuated.

Cleanup is underway of soil and vegetation contaminated by the chemical.

The rail line is privately owned by the oilfield services company Schlumberger. Ramos said the company is expected to pay for cleanup.

The company did not return a phone message Monday.

In a separate development, environmentalists in Vermont are planning a vigil this week to mark the third anniversary of the wreck of an oil train in Quebec that killed 47 people.

The group, 350-Vermont, said the July 6, 2013, accident in southeastern Quebec highlighted the dangers of the growing use of trains to ship crude oil.

The group will hold the event from 6 to 9 p.m. Wednesday at Burlington’s Battery Park, from which it says you can see across Lake Champlain to tracks on the New York side where oil trains travel regularly.

The Quebec accident occurred when an unattended freight train with 74 cars rolled down a grade from Nantes and derailed in the town of Lac-Mégantic. Several tank cars carrying Bakken Formation crude oil exploded.

Associated Press