Grace regained hurricane strength Friday as it barreled towards Mexico for a second time, triggering warnings of flooding and mudslides in mountains on the eastern mainland.

The hurricane first struck Mexico's Yucatan Peninsula on Thursday as a Category One storm -- the lowest on the five-level Saffir-Simpson scale -- near the town of Tulum, famed for its Mayan temples.

After losing strength, Grace's winds whipped back up to 90 miles (145 kilometers) an hour on Friday, as it moved over the Gulf of Mexico, according to the US National Hurricane Center (NHC).

"Air force hurricane hunters find Grace has strengthened into a hurricane," the NHC said, maintaining a warning zone stretching from Puerto Veracruz to Cabo Rojo, where the storm was expected to make landfall overnight.

As of 2100 GMT, Grace was centered about 115 miles (185 kilometers) northeast of the major port of Veracruz, and heading west towards the coast at a speed of 10 mph.

"Strengthening is forecast until Grace makes landfall, with rapid weakening expected as Grace moves inland over the mountains of central Mexico," the NHC said.

Troops on standby

Grace is likely to be upgraded to a Category 2 hurricane before it reaches the coast, Alejandra Mendez, general coordinator of Mexico's National Meteorological Service, told a news conference.

Authorities in the state of Veracruz said they had prepared 200 storm shelters and planned to open another 2,000 if necessary.

Veracruz Governor Cuitlahuac Garcia warned of the risk of flooding and mudslides as the storm dumps heavy rain on the mountainous region.

Members of the Mexican armed forces were ready to deploy if needed to protect residents, said civil protection national coordinator Laura Velazquez.

Businesses along the coast were packing up in preparation for the storm's impact.

"We've removed all the umbrellas (from the beach) because the tide is already rising," restaurant owner Victor Morales told AFP.

'Scare over'

As the hurricane approached Mexico's Yucatan Peninsula earlier in the week, more than 6,000 tourists and residents were evacuated to storm shelters across the southeastern state of Quintana Roo.

The storm passed the Riviera Maya coastline without any loss of life, said Quintana Roo Governor Carlos Joaquin. He said electricity had been almost completely restored across the state.

Workers were seen clearing up fallen branches and other debris in Tulum but the town escaped major damage.

"The scare is over and luckily everything turned out okay," said Sandra Rodriguez, a 39-year-old Argentinian tourist visiting Cancun.

Rodriguez admitted she had been worried because she was not used to such storms.

"I thought the hurricane was going to drown us," she said.

The storm toppled some trees and caused mostly minor damage in Quintana Roo and the neighboring state of Yucatan.

The NHC warned that heavy rainfall in Mexico through the weekend "will result in significant flash and urban flooding as well as mudslides."

A "dangerous storm surge" would be accompanied by "large and destructive waves" near the coast, the report said.

"Life-threatening surf and rip current conditions" could continue into the weekend, the NHC added.