Victor R. Caivano, Associated Press
Tourists watch the ocean from inside a swimming pool at a resort in Los Cabos, Mexico, Sunday, Sept. 14, 2014. Hurricane Odile turned into a Category 4 hurricane and it's expected to make a close brush with the southern portion of Mexico's Baja California peninsula Sunday evening.

SAN JOSE DEL CABO, Mexico — Hurricane Odile grew into a massive Category 4 storm and took aim at the resort area of Los Cabos on Sunday, prompting authorities to evacuate vulnerable coastal areas and prepare shelters for up to 30,000 people.

The U.S. National Hurricane Center in Miami said Odile was on a track to pass close to or directly over the southern end of the Baja California Peninsula by night and into Monday.

Odile's maximum sustained winds increased to 135 (215 kph), and its center was about 185 miles (300 kilometers) south-southeast of the southern tip of Baja California. Odile was moving to the northwest at 15 mph (24 kph).

David Korenfeld, director of Mexico's National Water Commission, described Odile as a "highly dangerous" storm.

High winds, deadly surf and heavy rains were possible for Baja and parts of the mainland. Some 800 marines were on standby, and officials readied heavy equipment to help out in areas where mudslides could occur.

In Los Cabos, skies clouded over as gusty winds whipped palm trees and waves pounded the rocky coastline. Fluttering black flags signaled that beaches were closed due to high surf.

Hotel officials were keeping guests updated about the storm's approach, and distributing movies and board games in anticipation of everyone having to hunker down inside later in the day. Guests were advised to have their bags packed and passports at the ready.

Ann Montalvo, a tourist from California who was staying at the Westin resort, said hotel workers seemed to be taking the right steps to ensure guests' safety, and she wasn't worried.

"I live in the San Francisco area where we have earthquakes, so we're always kind of on our toes anyway," Montalvo said.

A hurricane warning was in effect for Baja California Sur from Punta Abreojos to La Paz.

Mexican authorities declared a maximum alert for areas in or near Odile's path, and ports in Baja California were to remain closed.

Korenfeld said there was also a chance the storm could track into the Gulf of California, also known as the Sea of Cortez, and as a precaution authorities were on high alert.

Luis Felipe Puente, national coordinator for Mexico's civil protection agency, said 164 shelters had been prepared for as many as 30,000 people in the state of Baja California Sur. He said occupancy in hotels was low, but tourists were warned to stay inside in the safer areas of the hotels and keep away from doors and windows.

In the central Atlantic, Tropical Storm Edouard strengthened into a hurricane, although it was expected to remain far out at sea and pose no threat to land.

The Hurricane Center said Edouard had sustained winds of 80 mph (130 kph), was centered 915 miles (1,470 kilometers) east-northeast of the northern Leeward Islands and was moving northwest at 16 mph (26 kph).

Associated Press writer Maria Verza contributed from Mexico City.