Hurricane Maria hitting Puerto Rico

SAN JUAN, Puerto Rico (CNN) SAN JUAN, Puerto Rico (CNN) -- Thousands of Puerto Ricans heeded the calls of government officials and have taken refuge in shelters as the Caribbean island braces for Hurricane Maria's direct hit early Wednesday.

"As of 2:30 a.m. we count 10,059 refugees and 189 pets (in shelters)," a tweet from the island's governor, Ricardo Rosselló says. On Tuesday, he called Maria an "unprecedented" atmospheric system.

The record-breaking Category 5 hurricane -- with sustained winds of 175 mph (281 kph) --is the first storm of its strength to hit the US territory in nearly 80 years.

Conditions are expected to worsen between 8 a.m. and 9 a.m. Wednesday, when the storm's eye wall -- and the strongest winds that it will bring with it -- hit the eastern coast of the island.

As millions of residents hunkered down in their homes, others in the most vulnerable areas -- the low-lying, flood-prone areas -- have been evacuated.

The Puerto Rico Convention Center in San Juan -- which is still housing Hurricane Irma evacuees from other Caribbean islands -- is preparing to accept thousands of residents as the worst of the storm is felt.