Two men have been detained for allegedly burning two transgender women to death in Puerto Rico, police said Wednesday. The double killings are being investigated as a hate crime and the FBI has taken over the case after pleas from activist groups.

The bodies of Serena Angelique Velázquez Ramos, 32, and Layla Pelaez Sánchez, 21, were found burned inside a charred vehicle in Humacao, a coastal city in eastern Puerto Rico, last week. Juan Carlos Pagán Bonilla, 21, and Sean Díaz De León, 19, were taken into custody in connection with their deaths, police said.

Captain Teddy Morales, who oversees criminal investigations in the district, said one of the men confessed to his participation in the "vile" crime and admitted it was done for "reasons of revenge" by "repudiating the sexual orientation of the victims."

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After a review of the evidence, the FBI assumed jurisdiction over the case, police said.

Activists have raised alarm over the recent spike in murders against the trans community, calling it "an epidemic of anti-LGBTQ violence." According to the Broad Committee for the Search and Equity (CABE), a Puerto Rico-based LGBTQ group, there have been 10 murders of trans people in the last 15 months on the island. Five of them in the last two months, including the shooting death of a transgender woman known as Alexa. Video on social media showed her being threatened before gunshots were heard.

"They are hunting us and they are killing us," Ivana Fred, a CABE ally, said in a statement. "There is no other way to put it. In the past two months, five trans people have been killed in a resurgence of violence that we have not seen in our country for over a decade. We demand immediate and urgent action by the government to stop this wave of violence against our trans and LGBTQ people."