A gang of robbers armed with machetes hit Ladbrokes in Ovenden Road in Ovenden, Halifax last night.
The three men, all wearing balaclavas, burst in at 9.20pm.
They escaped with cash on foot but a vehicle could have been waiting for them.
Detectives are linking the theft to an attempted robbery at William Hill bookmakers in Keighley Road, Ovenden, last Saturday night.
There, three men, also wearing balaclavas, demanded money from staff but left empty-handed after workers threatened to ring police.
Detective Sergeant Terry O’Keeffe said police want to hear from anyone with information about either incident.
Anyone who witnessed them or saw anyone in the area acting suspiciously should call Calderdale CID on 01422 337086 or Crimestoppers, where information can be passed on anonymously, on 0800 555111.