Several major U.S. media websites were blocked to Europeans on Friday as the European Union’s new data protection law kicked in.

The websites of the Los Angeles Times, Chicago Tribune, New York Daily News and other publications owned by Tronc were down, showing the message: “Unfortunately, our website is currently unavailable in most European countries. We are engaged on the issue and committed to looking at options that support our full range of digital offerings to the EU market.”

News sites owned by Lee Enterprises, which include the Arizona Daily Sun and Star papers and the Times of Northwest Indiana, were also unavailable in Europe. A message on Lee Enterprises’ website and the websites of its subsidiaries read: “We recognize you are attempting to access this website from a country belonging to the European Economic Area (EEA) including the EU which enforces the General Data Protection Regulation (GDPR) and therefore cannot grant you access at the time.”

Websites run by U.S. media firm A+E Networks, including History.com and FYI, were also down in Europe, with a message merely saying: “This content is not available in your area.”

Tronc, Lee Enterprises and A+E Networks were not immediately available for comment when contacted by CNBC.

The EU’s GDPR was implemented on Friday. The new rules mean that firms must obtain explicit consent from customers in order to use their data. It also lets people request to see all the data firms have on them and to have the data deleted.

Major U.S. news sites like The Washington Post and The New York Times were unaffected. Others, including Oath-owned TechCrunch, the Huffington Post and Engadget, showed a message asking for users’ consent before letting them visit.

GDPR threatens to fine firms up to 4 percent of global annual turnover or 20 million euros ($23.4 million) — whichever is bigger — for violations.