The two suspects, 31 and 35, were detained across the border by mainland authorities following a joint investigation with their Hong Kong counterparts.
The pair are said to be on board a speedboat that struck a police vessel carrying a group of officers, including senior inspector Lam Yuen-yee, 37, near Sha Chau on September 25. The police patrol boat overturned and Lam’s body was recovered two days later.
Police said the two men were members of a cross-border smuggling syndicate.
“We are still investigating the case,” senior superintendent Ho Chun-tung from the Organised Crime and Triad Bureau told a media briefing on Monday.
“At this point, we are still doing whatever we can to assist in the whole investigation to make sure the whole group behind this incident will be revealed and arrested.”
Ho added that officers will step up cooperation with mainland authorities to tackle cross-border smuggling.