Hurricane Dolly toppled trees and sent billboards flying Wednesday in the Mexican city of Matamoros, and authorities south of the U.S. border warned of possible flooding.

No deaths were reported in Mexico from Dolly, which struck land just north of the border in Texas, but Tamaulipas state Gov. Eugenio Hernandez urged residents there to be alert for flooding because of the heavy rains.

"Dolly didn't leave behind any incidents for us to lament," Hernandez told reporters. But he said 50 neighborhoods in Matamoros are still in danger of flooding. About 13,000 people have taken refuge in 21 shelters.

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"Strong winds are no longer the problem. Now we have to worry about intense rain in the next 24 hours," Hernandez said.

Dolly weakened to a tropical storm late Wednesday night and was moving west near 7 mph (11 kph), forecasters said. Dolly is expected to continue weakening as it moves farther inland.

Mexican officials were monitoring the Rio Grande's water levels, which were at 13 feet (4 meters) before the storm hit. Eduardo Perez, spokesman for the Tamaulipas state water commission, said the river could reach 30 feet (9 meters) before overflowing.

• Click here to view photos of Hurricane Dolly in Mexico.

Authorities asked local factories to close so employees would not brave the rough weather, and most businesses were closed as the storm hit. In the few stores still open, shelves largely emptied by people stocking up on food and water.

About 4,800 soldiers and Tamaulipas state civil protection officials patrolled to prevent looting. Electricity was cut to the city of Matamoros to guard against electrocutions from downed power lines.

Authorities attempted to evacuate up to 23,000 people, but many refused to leave.

As rain and wind beat against his brick home outside Matamoros, 21-year-old Hector Gonzalez said he planned to ride out the storm in the kitchen with his younger brother and parents. Surrounding fields already were under water.

"The trees are really moving" in the wind, he said.

Maria Lorenzo Agustin, 49, said she was not taking any chances after losing her home and other belongings in past hurricanes.

"Last time a hurricane hit, we lost the roof and everything was destroyed inside the house," Agustin said.

She and her 102-year-old grandmother fled their wooden shack in the fishing community of Higuerilla and spent the night at a convention center-turned-shelter in Matamoros.

Alejandrina Salas, 53, abandoned about 60 chickens at her home in Manos de Leon and arrived at a Matamoros shelter Tuesday night carrying one bird.

"I love this one a lot," she said.

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