Story highlights In addition to three deaths, several dozen people are missing in Dominica

Tropical Storm Erika is expected to slide past Virgin Islands and Puerto Rico later Thursday

Erika could become Category 1 hurricane as it approaches South Florida on Monday

(CNN) Tropical Storm Erika doesn't have strong winds, but heavy rains were wreaking havoc on the Caribbean island of Dominica where three people were killed.

Prime Minister Roosevelt Skerrit said Thursday on social media that people were missing after floods wiped out roads and swamped villages.

"Our primary concern at the moment is for the preservation of life in Dominica," he wrote. "We are now going to be focused on a search-and-rescue mission. We will focus on infrastructure after."

The Caribbean Disaster Emergency Management Agency said 25 to 30 people were missing.

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