A man was seriously injured following a chemical spill on the Upper East Side on Tuesday morning.

An FDNY spokesperson said that around 25 gallons of sodium hydroxide were spilled on 61st Street near 5th Avenue just before 7 a.m. Firefighters in hazmat suits swarmed the scene, and one person was hospitalized with serious but non-life-threatening injuries, according to the FDNY.

First responders were still decontaminating the area as of 9:45 a.m., leading to extensive traffic delays on surrounding streets.

Sodium hydroxide, also known as lye, is a corrosive compound that may cause eye and skin burning, temporary loss of hair, and pneumonitis, according to the CDC. It's commonly used in manufacturing soaps, rayon, paper, explosives, dyes, and petroleum products.

It was not immediately clear what caused the spill.

This is an ongoing story. We'll update as more information becomes available.