MEXICO -- Hurricane Otis slammed into Mexico's southern Pacific coast as a catastrophic Category 5 hurricane early Wednesday, bringing dangerous winds and heavy rain to Acapulco and surrounding towns, stirring memories of a 1997 storm that killed dozens of people.
Now a Category 4 storm, the hurricane was expected to continue to weaken quickly in Guerrero state's steep mountains.
Otis had strengthened rapidly, going from a tropical storm to a Category 5 hurricane in 12 hours Tuesday.
Wind speeds approached 165 mph on Wednesday as the storm approached Acapulco, a Mexican resort town, at about 1 a.m. local time, according to a bulletin.
Flash flooding is also possible with up to 20 inches of rain are expected through Thursday in areas including Guerrero and the western coastal sections of Oaxaca, officials said.
Residents of Guerrero's coast scrambled to prepare, but the storm's sudden intensity appeared to catch many off guard.
"This rainfall will produce flash and urban flooding, along with mudslides in areas of higher terrain," the National Hurricane Center said.
"We're on maximum alert," Acapulco Mayor Abelina López said Tuesday night as she urged residents to hunker down at home or move to the city's shelters.
The storm was expected to remain at Category 5 hurricane through landfall before weakening as it moves over "the higher terrain of Mexico," the center said.
"Otis will likely dissipate over southern Mexico on Wednesday night," the bulletin said.
Otis is stronger than Hurricane Pauline that hit Acapulco in 1997, López said. Pauline destroyed swaths of the city and killed more than 200 people. Hundreds of others were injured in flooding and mudslides.
Between the internationally known resorts of Acapulco and Zihuatanejo are two dozen small towns and villages perched between the mountains and the ocean.
Otis' arrival came just days after Hurricane Norma struck the southern tip of Mexico's Baja California Peninsula to the north.
Acapulco is a city of more than 1 million people at the foot of steep mountains. Luxury homes and slums alike cover the city's hillsides with views of the glistening Pacific.
Guerrero is one of Mexico's most impoverished and violent states. Just Monday, a local police chief and 12 police officers were massacred and found on a highway in El Papayo, which is in the Guerrero township of Coyuca de Benitez not far from Otis' impact zone.
In the Atlantic, Hurricane Tammy continued moving northeastward over open water with winds of 85 mph (140 kph) after sweeping through the Lesser Antilles over the weekend. Tammy was located about 570 miles (915 kilometers) south-southeast of Bermuda. The storm was expected to become a powerful extratropical cyclone by Thursday, according to the U.S. National Hurricane Center.
The Associated Press contributed to this post.