"They'd smashed in the rear window with the bat and the passenger window with a broom. The kids responsible were chased -- there were four of them -- and two girls were caught. Two guys got away."
Police arrived and questioned the girls, who denied involvement.
Hospital staff also discovered a locked ambulance bay storage room was broken open. The broom used in the attack was stolen from the room, Mrs Williamson said.
One of the boys soon returned on a bicycle and the officers also interviewed him before returning him home in a police vehicle.
"He was only 15 and was completely drunk and had come back to gloat over what he'd done. I have no idea why they did that to my car but I think it was random and not a targeted attack," Mrs Williamson said.
"They were just wandering about at that time of night with a baseball bat, after drinking. What else were they planning on doing? They may have just been angry.
"It's all very scary when you think about it. I mean, I was heading out there. What if they took me as a good target as well?
"I hope the security is improved but we shouldn't have to. I mean we're professionals trying to help save them. The weekend before my colleagues tried to save those boys who were from Featherston.
"That was really hard on all of them. Yet these teenagers don't seem to have any idea what they put others through because of their decisions, their stupidity."
Mrs Williamson and her husband Paul say they shifted to Masterton with their 15-year-old son about a year ago. They had endured earlier difficulties with teenagers in the town, they said, but decided to remain despite more than once almost leaving the region.
Mr Williamson is to take their plight to Wairarapa MP Alastair Scott and Masterton Mayor Lyn Patterson, he said, and had sworn he would, with his wife, "fight to get our town back".
Mr Williamson was keen to join with like-minded people and mount community "observe and report" patrols, he said.
Anybody interested may contact Sarah Taylor-Waitere at Masterton Neighbourhood Support at 3788900 or 0211660627 or email mstns@connectingcommunities.org.nz For Carterton Neighbourhood Support, contact Sue Tennent at 027 9386998 or email ctns@connectingcommunities.org.nz For Featherston Neighbourhood Support call Robyn Ramsden at 027 8836036 or email fstns@connectingcommunities.org.nz