An exhibit at the Smithsonian's National Zoo remains temporarily closed after a chemical explosion in a mechanical building Thursday.
The American Trail will reopen Friday morning, the zoo said.
No people or animals were injured in the chlorine explosion, which happened shortly before 11 a.m. at the American Trail, one of the zoo's newer areas.
A contract worker was performing routine maintenance on the life support system located between the otter and beaver habitats on the trail when he smelled chlorine, the zoo said. The worker left the area, and then heard a boom.
D.C. Fire & EMS hazmat units were called to the zoo, located at 3001 Connecticut Ave. NW, out of an abundance of caution, the zoo said.
"Heard a bang at the @NationalZoo and now fire trucks rolling through. Hope everyone is safe," Karen Gaudette (@nwfoodette) tweeted.
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There was no smoke or fire, although the fire alarms sounded.
First responders evaluated the employee and said he is doing fine, News4's Meagan Fitzgerald reported.
The area around the American Trail remained closed as hazmat teams checked things over and then gave an all-clear at 2 p.m.
Zookeepers and vets conducted then conducted checks for safety and wellness. "All animals are accounted for and doing well," the zoo said in a release Thursday afternoon.
The rest of the zoo remained open Thursday.
The American Trail opened Sept. 1, 2012 after a $42 million renovation of the zoo's lower valley. In addition to beavers and otters, the trail is also home to seals, sea lions, bald eagles and other North American animals.
The building where the explosion occurred houses water-processing equipment for filtration and treatment systems, the zoo said. The equipment helps with water-quality monitoring and animal care.