Pirates attacked a South Korea-flagged cargo ship before dawn in the Singapore Strait and got away with thousands of dollars in cash and even the sailor’s shoes. The incident that took place in a busy sea lane left two people with minor injuries.

Officials from the Ministry of Oceans and Fisheries confirmed that seven pirates on a speedboat boarded the CK Bluebell. The Yonhap News Agency said, “a speedboat operated by the pirates approached the freighter at a speed above 20 knots. Afterward, seven weapons-wielding pirates got on board and assaulted the sailors for about 30 minutes.”

The attackers stole $13,000 and got away with 22-membered crew’s personal belongings, such as mobile phones, clothes and shoes.

According to Reuters, the cargo ship had set sail from its anchorage off Singapore late Saturday afternoon. The vessel was headed northeast to the Incheon port from Brazil. Reports say piracy has declined in the area where the incident took place, amid heavy policing by Singapore, Malaysia and Indonesia.

Earlier this month, the Chinese Ministry of Transport had raised its security recommendation for Chinese vessels in the Malacca Strait, between the Malay Peninsula and the Sumatra.

The Singapore police has not yet commented the incident.