SEOUL, South Korea (AP) — South Korean singer Go Eun-bi, better known as EunB, died after a van carrying her group Ladies’ Code crashed into a guard rail on a rain-drenched highway near Seoul, police said Thursday.

The 22-year-old Go’s bandmate RiSe, whose real name is Kwon Ri-sae, was seriously injured in the accident early Wednesday and remained in critical condition after undergoing emergency surgery, officials said. The band, which debuted last year, was returning to Seoul after recording a TV program in the southeastern city of Daegu, said police inspector Lee Ho-dong.

The group’s agency said another band member fractured a bone and two others had minor injuries and were treated for shock.

The driver, who was treated for a minor injury before questioning, may have been speeding on a wet road to meet a tight schedule, Lee said.

“We are investigating the exact cause of the accident. But it’s difficult because the highway section where the crash occurred did not have a closed-circuit television camera,” Lee said, adding that a camera from inside the van was sent to the National Forensic Service.

Lee said it would likely take about a month before it’s determined what caused the crash.