An 18-wheeler carrying roughly 3,500 gallons of sodium hydroxide overturned around 6:45 p.m. Tuesday while merging onto I-37 south from Loop 410.

Three of the 250 gallon containers onboard the truck leaked minimally, said SAFD spokesperson Christian Bove.

A HAZMAT team responded to the scene, which prompted police to shut down all lanes of I-37 south at 410 and both the east and westbound ramps from 410 onto 37 south.

Officials say the I-37 southbound exit ramp would remain closed until 10 a.m. Wednesday, but the main lanes were clear.

Police said it was unclear what caused the big rig to overturn. A second 18-wheeler headed in the opposite direction on Loop 410 was also trying to merge onto I-37 south at the same time.

When the first truck overturned, it clipped the second truck causing minimal damage.

The driver of the overturned 18 wheeler was taken to a hospital as a precaution. His injuries did not appear to be serious, according to police.

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