When terrorists attacked the Twin Towers on 9/11, police and fire officials in New York and around the country realized they had a problem: their radios couldn’t easily talk to each other.

Officials in Los Angeles came up with a plan to address that but the Los Angeles County Board of Supervisors vote Tuesday to stop construction after complaints from residents and cities.

“It absolutely puts the project in jeopardy,” said Patrick Mallon, who heads the Los Angeles Regional Interoperable Communications System - or LA-RICS. That’s the group created to shepherd $154 million in federal grants to build the system, meant as a "national model" for emergency communications.

“A number of questions and concerns have been expressed,” Supervisor Mike Antonavich wrote in a motion to hit the brakes. They include safety concerns by local residents from exposure to radio frequencies.

The board’s vote came despite pleas from Los Angeles Sheriff Jim McDonnell to keep the project on track. He told the board it's critical police and fire officials from the county's many agencies have the ability to easily communicate with each other.

"One day it may be a fleeing homicide suspect in a cross-county high speed car chase. The next day it may be a raging wild fire, an earthquake or natural or man made disaster,” he said.

The plan called for the construction of 177 new cellular towers atop fire stations and other sites to independently move data across emergency agencies. It would upgrade 62 existing radio communication towers to better handle radio traffic.

But amid project delays and changing federal requirements, only 14 new towers have been built. Another 40 were in various phases of construction before Tuesday's vote, according to Mallon.

Some cities have dropped out of the project, including Long Beach. Officials there complained about a more than one million dollar annual fee to participate, according to a report to the Board of Supervisors by county interim Chief Executive Officer Sachi Hamai. Other city officials have questioned whether the system is needed.

Hamai said Glendale dropped out last year, saying the city already has shared radio capabilities "through its partnership with other agencies."

Agencies can already talk to each other in some cases by switching frequencies on their radios. The issue is ease and speed in a time of crisis.

Some people who showed up at Tuesday's board meeting said they were concerned about the unsightliness of the new towers. Others were worried about radio frequency emissions. Attorney James Wald of Rolling Hills threatened to file a lawsuit to stop a planned tower at a fire station near his house.

“I’m going to protect my babies," he told the board, "and the people on my street with pacemakers.”

County public health officials gave assurances the towers would be safe. Baby monitors put out more emissions, according to Dr. Jerrold Bushberg of UC Davis, who spoke during the hearing.

But skepticism ran deep among some people, including Los Angeles County Fire Captain Lewis Currier.

“The FCC benchmarks that LA RICS is using are antiquated and industry controlled,” he said. The county firefighters union officially opposes the towers on top of fire stations.

The vote halts construction of towers on fire stations and any others that face community opposition. Mallon said he's unsure if any can resume construction at this point. Supervisors, many of whom expressed support for LA-RICS, urged Mallon to conduct more community outreach.

The board also voted to ask the federal government to extend a September deadline to complete part of the project. If the National Telecommunications and Information Agency refuses, L.A. County stands to lose millions of dollars in federal funding.