Four people have been arrested in connection with the kidnapping incident at Singamata Reef Resort off Semporna, Sabah late Wednesday.

The three men and a woman were brought in for questioning on Thursday to facilitate investigations, according to Sabah police chief Datuk Hamza Taib in a report in The Star.

“We are getting their statements and are continuing our investigations,” Hamza was quoted as saying by the English daily.

However, police have yet to obtain vital information which could help crack the case, he added.

Chinese tourist Gao Huayuan, 29, Filipina resort employee Marcy Darawan @ Mimi, 40, were abducted from the resort at about 10.30pm on April 2.

Three armed men wearing masks were seen entering the resort with four others waiting in a boat below the deck in the 30-minute raid.

Police believe the seven gunmen belong to a 'kidnap for ransom' group from the Southern Philippines, though, no ransom demands have been reportedly made so far.

The two victims are believed to have been brought across international waters and are now in the Philippines.

Gao is a student from Shanghai who arrived for a diving course. Police said she was likely a random victim.

Police were reportedly taking down statements from 49 resort staff and 61 guests – including 59 China tourists, a Malaysian and Iranian.

Investigators have said "insiders" may have aided the abduction of two women at the island resort as those without intimate knowledge of the resort would not have been able to easily access the resort grounds.

Semporna is a coastal town on the east coast of Sabah, covered under the Eastern Sabah Security Zone (ESSZONE) set up following the Lahad Datu intrusion by Sulu gunmen in February last year.