This story was updated at 4:37 p.m. and will continue to be updated as more information becomes available.

Richardson ISD canceled all classes Monday after a tornado ripped across Dallas County on Sunday night, causing significant damage. Thousands remain without power, according to Oncor Electric. The extent of the damage is still being determined. No major injuries have been reported.

A tornado confirmed by the National Weather Service touched down just after 9 p.m. Oct. 20 in northern Dallas and made its way east through Richardson. The city of Dallas has opened Bachman Recreation Center for people seeking shelter and currently has 12 residents checked in there, according to a news release.

On Monday afternoon, Texas Gov. Greg Abbott issued a disaster declaration for 16 counties, including Dallas, Collin, Tarrant and Rockwall counties.

Oncor reported that it had restored power to about 30,000 customers in its service area by mid-afternoon Monday. About 65,000 customers - 46,000 in the Dallas area that includes Richardson - remained without power, a spokesperson said. The company planned to have about 4,000 personnel, including mutual assistance from other companies, on the ground by Tuesday.

"The company remains focused on restoring power as quickly and safely as possible," the release stated.

A National Weather Service spokesperson said the agency has deployed teams to survey damaged areas in the following locations: the intersection of I-35E and Walnut Hill Lane in Dallas; Richardson and the east Dallas area; and the Rowlett and Garland areas.

"Due to substantial storm damage, power outages and unsafe conditions, all RISD schools will be closed on Monday, October 21," according to a message on RISD's social media accounts. "All school and district activities and will also be cancelled on Monday. At this time, RISD anticipates all schools being open on Tuesday, October 22."

An RISD spokesperson said the district decided to cancel classes because of power outages at multiple schools, road obstructions and buses being unable to refuel at an operations center. Some RISD schools, including Berkner High School and Springridge Elementary, were damaged in the storm.

Richardson Mayor Paul Voelker said first responders worked overnight to search for injured people, clear roads and repair utility services.

“There is a significant amount of damage that has severely impacted many of our residents,” Voelker said in a news release. “We have mobilized every department in the City and activated all necessary mutual aid agreements with our partners in the region and state to respond and recover from this event as quickly as possible."

The city of Irving also reported that a downed power line at Rock Island and Crandall roads resulted in classes being cancelled at Lamar Middle School.

Crews in Richardson are working to clear blocked roadways and downed traffic signals. The following major roads currently closed and under repair are:

-Centennial Boulevard between Bowser Road and Grove Road
-Abrams Road between Buckingham Road and Park Bend Drive
-Bowser Road between Centennial Boulevard and Buckingham Road
-Coit Road at Spring Valley Road (open but treated as a 4-way stop)

Richardson resident Jessica Gurganus said she found a tree had landed on the roof above her master bedroom.

“This tree actually sold this house for me," Gurganus said. "We’ve been here 20 years now. We kind of got lucky. Now it’s just cleanup.”

The city of Richardson stated it had received multiple reports damaged gas mains and downed power lines. To report a suspected gas leak or downed power line, call 911. The Atmos Energy 24/7 emergency line for gas leaks is 866-322-8667.

Atmos Energy has set up a command center at 10460 Shady Trail in Dallas for customers who have questions or would like to voice concerns. Its technicians responded to more than 200 emergency calls in the Dallas area after the storm and are continuing to survey the area, according to a release. The company is also using mobile detection vehicles that look similar to a Google Maps car to identify damage.

Customers or residents who would like to visit with a team member to voice any questions or concerns may visit the Atmos Energy Command Center at 10460 Shady Trail in Dallas.

For non-emergencies, including downed trees or other damage, Richardson residents can call city’s 24-hour response line at 972-744-4111.

The northbound Dallas North Tollway exit ramp to Royal Lane remains closed to traffic, the North Texas Tollway Authority reported on Monday.

The city of Dallas reported multiple streets in the north central and northwest portions of the city remain closed. Click here for the most recent information on street closures in Dallas.

Valerie Wigglesworth contributed to this story.