Don't think any of them escaped. Rumors said some escapes a couple days ago by climbing down from a bridge with motorcycles waiting to pick them up. Police only confirmed they caught 37 of them. 14 of the rioters might have escaped through the sewage system but not sure.
As of now, 1100 of the rioters got arrested in or nearby PolyU. 800 of them surrendered of which 300 of them are under 18(HKPF has agreed to not take people under 18 into custody but would take a photo and ID information and decide to press charge or not later.) HKPF believes that there might still be 2-300 rioters inside the PolyU.
Good. Time to cut HK's losses. Let them rot in prison at minimum until 2047. Also serves to get the extremist crybabies agitated enough to root them out and join the pothole.