Where are the police?? So "efficient"

In the wee hours today at about 4plus, mom and myself were woken up by this rackus opposite our block.(at Tampines) At first it was a guy shouting vulgarities, car door slamming etc..There were a couple of guys a girl and then we heard someone got slapped and a woman wailed. (she sounded drunk to me) and then there were some commotion. And somehow we dunno from where some other turned up and probably "watched". Dunno lah, I could have reported the wrong number of people at present site but can't blame me if we were all still so blur after being roused from our sleep and our view were partially blocked by a tree. Cars came and go, nobody offered to help. The altruistic me decided to call 999 to report the incident, and hey! Where are the police?? For good whole 15 minutes after I called the incident continued. Someone came by in a motorcycle, and at first we thought it was the police (but police in motorcycle??) but it was a guy who told them. Well, I can't make out what he told them but all I know is he was snapped back with a loud "you shut up." And probably close to 4.50 or 4.50+, I saw the victim being carried to the block, probably up to her flat or maybe kena raped at the stairs??? I can't see what happened but for sure there were no more shouting or slapping or wailing. At 5.05am I heard cars coming and pick up some people and left, infact we did notice 3 other guys squatting at the carpark smoking. But eventually everyone left at 5.05am.
So during the whold episode where were the police?? If someone was beaten (as what I had reported), the assaultants would have finished the job in less than 15 minutes and run away. Who would be so stupid to stay behind and get caught??
Mom also did say "well, during the recent fire at Blk 261 the firefighters came first and after a long long time, the police then came." And you know what my dear friends?? The NPP is only 1 block away!!!