(KRON) — The evacuation order that some San Pablo residents were under for more than a day will expire at 9 p.m. Thursday, the San Pablo Police Department said. Residents on John Avenue and Stanton Avenue will be allowed to return home.

Five homes still must remain vacant as crews complete the removal of hazardous materials found in the area.

An evacuation center was set up at the Contra Costa Community College Gym at 2600 Mission Bell Drive parking lot 6.

The city says only to bring essential items that can be carried. Pets must be in a carrier or on a leash.

The city asks that residents only call to report a life-threatening emergency. If you cannot leave your home without help, call 911.

According to Captain Chris Toler with the Contra Costa County Fire Protection District, neighbors said the homeowner passed away a few months ago. The homeowner’s brother was in the process of cleaning up the property when he discovered hazardous chemicals. According to neighbors, the homeowner was a professor and chemist.

Various types of hazardous chemicals were found in the shed of the backyard, according to Captain Toler. Bomb Squad and HazMat crews are working to identify, contain, stabilize, transport and properly dispose of each of the chemicals which were said to be found in “improper containers.”

“Due to the classifications of materials or hazardous materials, there are some explosive classes of products in that particular shed,” said Toler.

CCFPD could not give an estimated time of when the evacuation would be lifted and is asking for residents to be patient as they work to safely remove the chemicals. No indications point to a possible meth or drug lab, the captain said.

Toler said the reason why crews have to work slowly is because most of the containers were not labeled, causing a longer process for testing and identifying each chemical.

Some chemicals have been removed and disposed of since being discovered.

At 6:10 p.m., Con Fire said the situation was still ongoing. Hundreds of boxes containing some known materials and some unknown materials were reportedly found.

Fire and police units are on the scene, and people are being advised to use alternate routes and avoid the area. They will be working until midnight.

The Contra Costa County Fire Protection District is also on the scene, according to a tweet. A photo accompanying the tweet showed two first responders’ vehicles in what looked like a residential area.

This is a developing story. Check back for updates.