Alameda will pump the brakes but move forward with a plan to scan the license plate of every vehicle entering and leaving the island city after a marathon City Council meeting saw residents and others raise concerns about privacy and whether the data would be shared with federal immigration officers.

The council unanimously agreed early Wednesday to earmark $500,000 for crime-fighting technology after police asked for 13 license plate readers that they hope will prevent or solve burglaries and other crimes. Before police can buy the devices, though, the city must contract with a vendor and revise its policy on how the information will be used and who will get to see it.

The decision sought to balance residents’ frustrations over a rash of car break-ins and thefts with concerns about the spread of mass surveillance. Some council members were wary of funding the scanners and questioned whether they would make the city safer.

“It would essentially create a virtual wall around Alameda without actually increasing safety,” said Vice Mayor Malia Vella, who nonetheless voted to set aside funding.

Several members of the public who addressed the council during a four-hour debate that stretched past midnight speculated that people worried about their privacy might avoid Alameda and its businesses because of the cameras.

Some of the five council members questioned Police Chief Paul Rolleri’s preferred vendor of the license plate readers, Vigilant Solutions of Livermore, which recently entered into a contract to provide data to U.S. Immigrations and Customs Enforcement, known as ICE. Alameda ordinances and state law restrict local cooperation with federal immigration enforcement.

The scanners are designed to capture images of all license plates that pass them, storing the data while flagging stolen or wanted vehicles and relaying that information immediately to law enforcement.

The city has scanners provided by Vigilant Solutions mounted on four police cruisers. But the City Council meeting made clear that significant questions remain about the strategy.

Rolleri said he didn’t have numbers revealing whether the cameras mounted on cruisers have made a difference. He cited the experience in Piedmont, which blanketed much of its border with Oakland with license plate readers in 2014. Property crime has since dropped 34 percent, officials said.

In addition, council members and public speakers questioned whether Alameda would be able to guarantee information never falls into the wrong hands, including ICE.

City officials said they were unaware until recent days that Vigilant Solutions had entered into a contract to turn over data to ICE in January. Information collected by the scanners on Alameda police cruisers was accessible to federal immigration authorities last month, and perhaps in years past.

Rolleri said he cut off that access last week and that it was unclear whether ICE had used any of the information. The chief said that if the city moves forward with the camera plan, license plate scans would be stored for six months to aid in investigations and would not be shared with ICE.

Council members expressed concern about doing business with Vigilant Solutions, given its contract with ICE, and ordered staffers to put the contract for license plate readers out to bid.

The police proposal, as it stands, is to put 13 license plate recognition systems on bridges, the Posey and Webster underwater tubes and at intersections near the city’s border with Oakland.

A majority of those who spoke at the council meeting opposed the idea, saying it was an affront to civil liberties and would make Alameda look like a frightened enclave.

“Alameda is a warm and inviting community,” said Vidia Gillula, 32. “I’m afraid if we surround our beautiful island with cameras, we will lose that. I don’t want to live in a city where everyone who comes in and out is a suspect.”

Camera supporters, though, spoke passionately about safety trumping all else.

“I’m concerned with privacy issues,” said Michael Robles-Wong. But, he added, he is more worried about the security of his family and neighbors, noting: “It is important to keep Alameda a safe, small island.”

Alameda saw a spike in crime over the previous two years, although overall crime is near 30-year lows, Rolleri said. In 2017, there were 5,075 crimes reported — a 12.4 percent increase that was largely due to grand theft and petty theft, officials said.

Overall, crime has declined 52 percent over the past three decades, police said. Rolleri said residents are responsible for about half the city’s crimes.

Information gathered by license plate scanners is made available to many local, state and federal agencies through a multiagency partnership called the Northern California Regional Intelligence Center. An investigator looking to pinpoint the past locations of a vehicle can run a plate through the database.

Jill Tucker is a San Francisco Chronicle staff writer. Email: jtucker@sfchronicle.com Twitter: @jilltucker