Authorities in Hong Kong are investigating apparent firebomb attacks outside the police headquarters and a police station.

Police say a man threw an ignited glass bottle toward a police vehicle Friday morning before fleeing in a car. The bottle landed next to the vehicle, which was outside police headquarters.

Hong Kong media reported that a second firebomb went off in the afternoon near a police station elsewhere in the semi-autonomous Chinese territory.

No one was reported injured in either incident.

The attacks come as police brace for what is expected to be a major protest on Sunday against proposed changes to Hong Kong's extradition law that would allow some suspects to be sent to mainland China to face charges.