South Korean band BTS, or the Bangtan Boys, kicked off the U.S. leg of its “2017 Live Trilogy Episode III The Wings Tour” with a power-packed performance at the Prudential Center in Newark, New Jersey, amid tensions over death threats targeting band member Jimin.

The seven-member K-pop group — made up of Rap Monster, Suga, J-Hope, Jungkook, V, Jimin and Jin — embarked on a world tour earlier this year with a performance in Seoul, followed by shows across South America. The band also made an appearance at the KCON 2017 in Mexico.

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The Prudential Center was initially supposed to host the band for one performance on March 24 but another show was added to accommodate the overwhelming demand for tickets. BTS’ first U.S. performance of the tour was held last Thursday. The K-pop band is now set to perform at the Allstate Arena in Rosemont, Illinois, on Wednesday, followed by shows at the Honda Center in Anaheim, California, on April 1-2.

However, there have been fears regarding the safety of band member Jimin after it emerged that some Twitter accounts said they will attempt to kill him during the concert in California. BTS’ loyal fan base, who are referred to as the A.R.M.Y., took up the matter with the group and its management, Big Hit Entertainment.

One Twitter account, along with the death threats, posted pictures of dead animals, bloody hands and guns, in an attempt to scare the group before their performance. The account has since been deleted. BTS’ management said they were looking into the matter.

“We believe that it is a joke by an anti-fan, but we are taking measures just to be sure,” Big Hit Entertainment was quoted as saying by Soompi on Monday. “We are working with the local staff and police to enhance the security.”

Staff at the Honda Center in California also said, “We are aware of the controversial social media posts. We will work to increase security around the venue.”