Firefighters found an artillery shell at a factory that was burning in Cuernavaca, the capital of the central Mexican state of Morelos, police said.

The anti-aircraft shell was found at a cosmetics factory in Cuernavaca, located about 90 kilometers (56 miles) from Mexico City, the police department said.

Firefighters found "a green-colored missile approximately 90 centimeters (about three feet) long, with a black point, and the words '106 r drill inert CARY M368,' which was seized by the Mexican army," the police department said.

William Andres Hernandez, the factory's 25-year-old manager, was arrested by the army.

Paramedics treated a woman in her 40s for smoke inhalation.

The fire was apparently caused by a gas leak, the police department said.