Apple will lay off 190 employees in Santa Clara and Sunnyvale in its self-driving car division, the company said.

The layoffs were disclosed, along with new details, in a letter this month to the California Employment Development Department. CNBC reported last month that layoffs were occurring in the self-driving car division, known as Project Titan. Tom Neumayr, an Apple spokesman, confirmed that the letter to the state referenced the same layoffs.

Most of the affected employees are engineers, including 38 engineering program managers, 33 hardware engineers, 31 product design engineers and 22 software engineers. The layoffs will take effect April 16, according to the filing.

Apple’s expansion into Santa Clara and Sunnyvale, which are close to the company’s headquarters in Cupertino, ramped up starting in 2014, according to property records and previous news reports. That was the same year the self-driving division was founded.

The layoffs coincide with falling iPhone sales, with revenue dropping by 15 percent in the last three months of 2018. An economic slowdown in China is also hurting Apple's business.

“A sudden and significant shortfall in iPhone revenue is causing a level of distress within Apple that is forcing it to make hard choices,” wrote Lynx Equity Strategies in an analyst report last month that speculated the self-driving car division could be shut down.

Apple previously cut hundreds of jobs in the self-driving car division in 2016, as it shifted from building its own car to developing software, Bloomberg reported at the time. More recently, Apple partnered with Volkswagen and is working to convert the German car maker’s T6 Transporter van into a self-driving employee shuttle, the New York Times reported last year.

Apple’s autonomous vehicle competitors include General Motors’ Cruise, Tesla, and Waymo, a subsidiary of Google parent Alphabet.

Apple performed 79,745 miles of testing in California between Nov. 30, 2017, and Dec. 1, 2018 — far less than two top competitors, Waymo of Mountain View and Cruise of San Francisco, according to DMV data this month.

For the same time period, Apple reported that its autonomous system had an error or a human driver took control every 1.1 mile. By comparison, Waymo had a disengagement every 11,017 miles and Cruise had one every 5,204 miles.

As of 2016, Apple had 25,000 employees in the Bay Area.

Apple’s layoffs span eight office and industrial properties: 3000 Kifer Road, 3689 Kifer Road, 5301 Patrick Henry Drive, 2945 San Ysidro Way and 2975 San Ysidro Way in Santa Clara, along with 1150 Kifer Road, 1170 Kifer Road and 195 N. Wolfe Road in Sunnyvale.

Roland Li is a Chronicle staff writer. Email: roland.li@

sfchronicle.com Twitter: @rolandlisf