Just 15 minutes into what was supposed to be a celebratory event marking the launch of Massachusetts' first e-scooter pilot program Monday, Brookline police officers were tending to a woman who had bloodied her head in an apparent accident involving one of the two-wheeled vehicles.

This could hardly be the scene that two leading scooter companies, Lime and Bird, envisioned when they called a press conference and staged a live demo outside Brookline Town Hall. As officials from the town and the two firms addressed reporters, an ambulance siren wailed in the background.

The injured woman was identified as Kim Smith, 62, of Brookline by her partner, Dan Weiner. She was wearing a helmet and appeared to have been riding a Lime model. Smith was stretchered into an ambulance and taken to a nearby hospital.

Reached by phone later, Weiner said Smith had simply lost her balance. She might need a couple of stitches, he said, but will be fine.

"As her partner, my opinion of this whole program went down a lot, but that's the way it is," Weiner said. "It was already approved, so I guess it's already Brookline now."

The scooter-share program is approved for now, but the pilot period ends in November. Then town officials will decide whether to make the program permanent.

In an interview after the launch event, Scott Mullen, Lime's director of Northeast expansion, said he wanted to learn more about the accident.

"I need more details," Mullen said. "Was she hit by something? Was there a banana peel? We'll figure it out. Let me get the facts, and we'll figure it out."

First responders treated Smith as she lay on the pavement in the Town Hall parking lot, the start and finish of a short, test-drive route available to Brookline residents and city employees who wanted to try the newest transportation mode available to them.

Daniel Farrell, a city launcher for Bird, led riders along the course and offered lessons but did not wear a helmet, as required by town regulations.

Brookline is the first municipality in Massachusetts to make electric scooters available for rent. The pilot features 200 scooters, split evenly between Lime and Bird. Both companies' vehicles top out at 15 miles per hour. Rentals cost $1 upfront and $0.15 per minute after that.

Bird briefly put scooters on the streets of Cambridge and Somerville without permits last summer but withdrew when those cities threatened to seize the vehicles.

Cities in Massachusetts have been slow to grant permits because the scooters do not comply with a state law requiring turn signals and brake lights. But with multiple bills in the state Legislature that would remove those requirements, including one measure proposed by Gov. Charlie Baker, Brookline, Boston and other municipalities are giving scooters a green light.