They shouldn’t have escalated, but they were potentially within their rights to. For all they knew they’d surrounded their knife robbery suspect.
Like, the best course of action would’ve been for her to say she lived there and deny being at the store, and tell them she’s pregnant so hopefully they’d realise she didn’t fully match the description and leave her alone. Hell, even telling them who she was and getting arrested for her outstanding warrant (which no doubt influenced her behaviour) would have been better than getting killed.
Ultimately it was the worst outcome. While the police perhaps didn’t do enough to avoid it and de-escalate, they were acting within their authority for chasing down a robbery suspect.