A San Francisco technology company laid off a group of software engineers as they were trying to join a labor union, according to a complaint filed with the National Labor Relations Board.

The Communications Workers of America claims Lanetix, which makes cloud-based software for transportation and logistics companies, violated federal labor laws by cutting 14 software engineers in January in San Francisco and Arlington, Va.

Most of the engineers were fired Friday, about 10 days after they filed a petition seeking union representation, according to the complaint filed by the CWA’s Washington-Baltimore Newspaper Guild. A hearing to determine a date to hold the union vote was scheduled for Thursday.

Lanetix did not immediately respond to several messages left by The Chronicle. On Thursday afternoon, a man who answered the company’s main phone line hung up on a reporter’s call.

While unions have made inroads in representing Silicon Valley bus drivers, security officers, food service workers and custodians, the Lanetix case could break new ground because union activity is still unusual for software engineers, who are generally highly paid and in short supply, labor lawyers said.

“Generally, Silicon Valley employers are deeply hostile to the idea of unions,” said William Gould, a Stanford Law professor who was National Labor Relations Board chairman under the Clinton administration.

According to the Labor Department, the median pay for software developers across the country in 2016 was $102,280. And the department projected there will be more than 10,000 job openings for software developers this year in California alone.

But there are other reasons unions can attract higher-paid tech workers, including “if you feel mistreated by the company or if you feel there’s favoritism going on or lack of job security,” said labor law attorney Steve Hirschfeld, founding partner of Hirschfeld Kraemer of San Francisco.

“There’s a myth that if you’re a highly paid employee, you either can’t join a union or wouldn’t be interested,” Hirschfeld said.

The Lanetix case is “significant because it is a tech company and they’re well-paid engineers,” he said. “That’s still a rarity today for that group of employees to be organized. (But) the feeling among many tech workers is that they’re viewed as being expendable.”

The Lanetix engineers signed union cards to join the CWA’s Washington-Baltimore News Guild. (The Pacific Media Workers Guild, which represents some San Francisco Chronicle employees, is also affiliated with the CWA.) According to the complaint filed with the board, the union said Lanetix began “threatening and coercing employees” for engaging in union activities starting in November. The complaint said one engineer was fired for participating in group discussions on Slack, an internal messaging service.

The union filed a petition with the board on Jan. 16 to represent the workers. The company terminated “all engineers and senior engineers in retaliation for demanding recognition,” the complaint said.

The engineers were called into a meeting and told of layoffs due to the company’s lackluster fourth quarter performance, CWA organizer Melinda Fiedler told Bloomberg Law.

“By the time they left that meeting, their computers were gone,” Fiedler said.

Cet Parks, executive director of the Washington-Baltimore News Guild, said the workers were told the company was moving engineering offices to Europe.

Benny Evangelista is a San Francisco Chronicle staff writer. Email: bevangelista@sfchronicle.com Twitter: @ChronicleBenny