ATLANTA, Georgia (CNN) -- Atlanta was scrambling back to normalcy Monday, but city officials warned it could take time to clear the devastation left by a tornado that swept through the city's downtown Friday evening.
The storm damage made travel even more difficult in a city where traffic and road construction already make commutes tedious for thousands.
Drivers were warned to exercise caution and patience coming into the downtown area, which still bore the wounds of the Friday twister. The tornado, which packed winds of up to 130 mph, slammed into skyscrapers as well as landmarks like the CNN Center and the Georgia Dome, where thousands had gathered for the Southeastern Conference basketball tournament.
"You are coming into a zone that has a lot of safety issues," Atlanta Police Department spokeswoman Judy Pal said at a Sunday news conference. She added that if you don't have business downtown, "please stay out of the city."
Dozens of streets remained blocked Monday as cleanup crews gathered debris and downed limbs and trees, piling it on sidewalks or in Dumpsters that had been lugged into cordoned-off roads.
As of Sunday afternoon, there were still three dozen trees blocking streets in the city, according to Mayor Shirley Franklin's office.
Traffic lights were on the fritz throughout the city. Several hung dark or blinking from power lines. One seemed to be hanging by a lone wire. Others were missing altogether.
On Sunday, crews were still working to repair scores of traffic lights throughout the city, said Donna Owens, the city's deputy commissioner of public works. Two neighboring counties were helping with the repairs.
The mayor's office advised people traveling downtown to take public transit.
Some streets were blocked as a safety precaution. Several tall buildings were still missing windows. Even a light breeze could cause glass to fall to the street or sidewalk, Pal said.
Broken windows were scattered around the cylindrical facade of the 73-story Westin Peachtree Tower, and curtains could be seen flapping from the rooms now open to the elements.
Ed Walls, the hotel's general manager, told WGCL-TV that about 100 windows were knocked out of the iconic Atlanta hotel. Guests were relocated, Walls said, noting there were no injuries reported in the hotel. Though the hotel is operational, it could take months to repair the damage, Walls told the television station.
The twister had winds of 130 mph making it an EF-2 on the enhanced Fujita scale of intensity used by meteorologists. It was an EF-1, with winds of about 100 mph, when it hit the heart of downtown.
The Red Cross was planning to open two service centers Monday to handle casework for victims. The agency was serving meals and counseling victims over the weekend. On Sunday, 45 people remained in one of the agency's shelters, said spokesman Ruben Brown.
"The good news is, the power's coming back up. Folks are able to get back in their homes," Maj. James Siler of the Salvation Army said Sunday. He said the organization was scaling back its mobile food efforts, but had about 1,000 food boxes ready to provide to families through emergency assistance agencies.
The agency also was using three roving canteens, which were providing hot meals and beverages to victims.
Buzz Weiss, spokesman for the Georgia Emergency Management Agency, noted that 22 counties in the state were impacted by severe weather Friday and Saturday. Two people were killed in storms Saturday.
Franklin and Georgia Gov. Sonny Perdue declared states of emergency Saturday, freeing up resources for aid.