Three men were found dead Thursday morning at a residence in Norwalk, and nearby residents were evacuated from their homes while authorities worked to determine if drugs or chemicals were involved in the deaths.

Paramedics responded to the home in the 12000 block of Portugal Court, near Cobos Street, south of Alondra Boulevard, about 3 a.m., according to the Los Angeles County Fire Department.

The men, reportedly in their 30s, were found lying on the ground in the home’s backyard, the sheriff’s department reported.

“The preliminary investigation has revealed that chemicals and possible narcotics were discovered at the location,” the sheriff’s department said.

A hazardous-materials team was sent to assist in processing the scene.

“Detectives are on scene and processing and assessing the situation,” sheriff’s Lt. Charles Calderaro told reporters late Thursday morning.

Two women who were in the residence along with two children were taken to a sheriff’s station, Calderaro said.

Nearby homes were evacuated “out of an abundance of caution,” according to the sheriff’s department.

All three men lived in the home, and two had girlfriends who live at the location, according to KTLA5. One man had two young daughters who were at home at the time, Channel 5 reported.