SEOUL, South Korea (AP) — A fire at a lithium battery manufacturing factory near South Korea’s capital on Monday left one person dead, three injured and more than 20 others missing, officials said.

Local fire official Kim Jin-young said rescue efforts were underway at the factory at Hwaseong, just south of Seoul.

Kim told a televised briefing that 23 people were reported missing but their identification is difficult because a register of the staff was believed to have burned. He said the missing people included foreign nationals including Chinese.

He said the mobile phone signals of the missing people were tracked to be coming from the second floor of the factory.

South Korean media reported about 67 people were working at the factory before the fire occurred.