Crossbows depending on type can be a real bitch to reload. Some newer types have become easier but still it takes enough time between shots for someone to escape. I would speculate that these women were tied up and then shot.
Crossbows can be real power killers. You can kill a grizzly bear or a adult male moose with a full sized crossbow the bolts will go completely through a 1200 lb moose. Reloading a 250# pull crossbow is done with a good strap and both arms in a rowing type motion. If these poor people were bound together it’s possible one shot went through all of them at once. I have shot 200lb adult boar with a crossbow the bolts was never recovered it broke the off side shoulder on the way out. Humans are frail compared to a boar or a moose. The UK has guns it’s a bugger to get the permit for one long arms mostly as pistols make the bobbies wet themselves.