Tucson Fire crews at the scene of a hazardous materials incident on the south side.

Six people took themselves to the hospital Wednesday night after apparently becoming exposed to toxic material released by coral in a fish tank, fire officials said Thursday.

Tucson Fire crews were called Thursday morning to check for hazardous materials at the single-story home near Interstate 19 and West Valencia Road.

Fire officials said six people took themselves to the hospital late Wednesday after becoming sick. The Tucson Fire Department was not called until Thursday morning.

Hazardous materials crews went into the home this morning around 10 a.m. to check for hazardous materials.

A fire official said on Facebook the incident apparently involved toxins released by coral in a fish tank.

The house was deemed safe by about 11:30 a.m.

Certain types of coral release what's called palytoxin, when cut or scraped. The toxin can cause severe respiratory reaction and death if ingested.

Zoanthid coral are common in home aquariums. They are considered relatively easy to keep and are often recommended to new aquarium owners. However, they can release toxins that are dangerous to humans, according to a report by the Centers for Disease Control and Prevention.