SAN JUAN, Puerto Rico — Hurricane Maria barreled toward Puerto Rico on Tuesday night after wreaking widespread devastation on Dominica and leaving the small Caribbean island virtually incommunicado.

As rains began to lash Puerto Rico, Gov. Ricardo Rossello warned that Maria could hit “with a force and violence that we haven’t seen for several generations.”

“We’re going to lose a lot of infrastructure in Puerto Rico,” Rossello said, adding that a likely islandwide power outage and communication blackout could last for days. “We’re going to have to rebuild.”

Authorities warned that people in wooden or flimsy homes should find safe shelter before the storm’s expected arrival Wednesday.

“You have to evacuate. Otherwise, you’re going to die,” said Hector Pesquera, the island’s public safety commissioner. “I don’t know how to make this any clearer.”

The warnings came after Dominica Prime Minister Roosevelt Skerrit sent out a series of dramatic posts on his Facebook page as the storm blew over that tiny country late Monday — but then stopped suddenly as phone and Internet connections with the country were cut.

“The winds are merciless! We shall survive by the grace of God,” Skerrit wrote before communications went down.

A few minutes later, he messaged he could hear the sound of galvanized steel roofing tearing off houses on the small rugged island. He said that even his own roof had blown away.

In the last message before falling silent, he appealed for international aid: “We will need help, my friends, we will need help of all kinds.”

The storm knocked out communications for the entire country, leaving anyone outside Dominica struggling to determine the extent of damage, though it was clearly widespread. “The situation is really grave,” Consul General Barbara Dailey said in a telephone interview from New York.