The 'navy-like ship' sounds like Marine Police and the 'glowing things that fall' sound like flares. There may have been a spike in recent attempts to enter the territory. I saw rings of lights like you describe in the same exact area in 2010. Aside from people smuggling, other goods are smuggled out of HK all the time, including electronics and timber from native trees that are pretty much extinct on the mainland.
EDIT: 'Glowy' things fired during the day doesn't make much sense though.