By Tim Higgins & Jack Nicas, Wall Street Journal-

Google parent Alphabet Inc.’s heated rivalry with Uber Technologies Inc. over self-driving cars has spilled into the courthouse, after the internet giant sued the ride-hailing company for allegedly stealing trade secrets to jump-start its own autonomous vehicle program.

Anthony Levandowski, a former key manager in the Google self-driving car project, is accused of secretly downloading 14,000 files in December 2015 before departing Alphabet last year to create Otto, a self-driving truck maker acquired last year by Uber.

This information was allegedly used by Uber to develop a laser sensor for self-driving navigation, according to the lawsuit filed by Alphabet’s Waymo LLC unit on Thursday in U.S. District Court in San Francisco.

 “We take the allegations made against Otto and Uber employees seriously and we will review this matter carefully,” said an Uber spokeswoman, who declined to make Mr. Levandowski available.

Waymo claims other former employees who are now at Uber also allegedly downloaded confidential information about the laser sensor before they left Waymo, including supplier lists and manufacturing details.

“Defendants leveraged stolen information to shortcut the process and purportedly build a comparable (laser sensor) system in only nine months,” Waymo’s complaint said.

Waymo said in a blog post Thursday that it spent thousands of hours and millions of dollars to develop its proprietary laser-sensor system. “Misappropriating this technology is akin to stealing a secret recipe from a beverage company,” the company said.

Among the records allegedly taken by Mr. Levandowski, according to the suit, were the circuit board designs for Waymo’s lidar, or light detection and ranging system used to guide a vehicle. Waymo said in the suit that a vendor “inadvertently” copied one of its employees on an email in December 2016 discussing an Uber project that contained the machine drawing for Uber’s circuit board that “bore a striking resemblance” to Waymo’s design.

Waymo alleges in the suit that a month before Mr. Levandowski left the company in January 2016, he “took extraordinary efforts to raid Waymo’s design server and then conceal his activities.” Mr. Levandowski allegedly installed special software on his company laptop to access the specific computer server, and then downloaded 9.7 gigabytes of confidential data from it, according to the suit.

He then attached an external hard drive to his laptop for eight hours, before erasing the history of his computer, the suit said. After that, he used his company laptop for another few minutes, “and then inexplicably never used it again,” the suit said.

The suit alleges that on Jan. 14, 2016, Mr. Levandowski met with high-level Uber executives at Uber’s headquarters in San Francisco. A day later, he allegedly registered the company that would become Otto, initially calling it 280 Systems, the suit said. Twelve days later, he left Alphabet, according to the suit.

Uber bought Otto for $680 million in stock in August 2016—shortly after Mr. Levandowski received his final multimillion-dollar compensation check from Alphabet, the suit said.

The suit is the latest salvo in the friendship-turned-rivalry between Alphabet and Uber. In 2013, Google’s venture arm invested $258 million in Uber, and longtime Google executive David Drummond joined the startup’s board. Google has let users book Uber rides in its Google Maps app, and Uber has also used Google’s mapping software to underpin its ride-sharing service.

But as Uber has expanded its size and ambitions over the past two years, the two companies have increasingly been on a collision course.Beyond self-driving cars, Uber has begun developing its own mapping software and started a package- and food-delivery service that competes with a similar Google offering. Google’s Waze navigation app, meanwhile, is expanding its own ride-sharing service that lets users carpool with each other to work.

In August, Mr. Drummond said he left Uber’s board “given the overlap between the two companies.”

The suit comes at a rough time for Uber, which is reeling from sexual harassment charges from a former software engineer. The company this week hired former U.S. Attorney General Eric Holder to investigate the claims and promised to make changes to its human resources department to better handle complaints of sexism and harassment.

Waymo’s lawsuit follows one filed by Tesla Inc. last month in a California state court against the former director of its Autopilot program Sterling Anderson and Chris Urmson, the former chief technology officer of Google’s self-driving project. Tesla has accused the two of improperly recruiting people away from the auto maker to work at their newly formed autonomous car startup. The startup has denied wrongdoing.