TULUM, Mexico &#8212 Hurricane Dean strengthened into a monstrous Category 5 storm Monday night as its first rain and winds began slamming the coasts of Mexico and Belize. Thousands of tourists fled the beaches of the Mayan Riviera as it roared toward the ancient ruins and modern oil installations of the Yucatan Peninsula.

By 8:35 p.m. EDT, it had sustained winds of 160 mph and was centered about 210 miles south-southeast of Tulum, according to the U.S. National Hurricane Center said. The eye was expected to strike the Yucatan region early Tuesday morning. Category 5 storms – capable of catastrophic damage – are rare with only three have hit the U.S. since record-keeping began.

Officials evacuated rustic lodgings south of Cancun, where Dean – which has killed at least 12 people across the Caribbean – was expected to smash ashore early Tuesday.

A hurricane warning was in affect from Cancun all the way south through Belize.