Three people were killed on Saturday at a restaurant in central Moscow following a massive explosion.

The explosion was caused by a homemade explosive device, Russia's National Anti-Terrorism Committee claimed.

The dead included a woman who attempted to bring the explosive device into the restaurant, a security guard and a patron, Russian state news agency RIA Novosti reported.

At least 21 more people were injured in the explosion, which happened around 8 p.m. on a ground floor terrace restaurant at Kudrinksaya Square, which includes seven skyscrapers built during the Stalin regime.

A Russian outlet said the explosion happened at the Balzi Rossi Italian restaurant. Its website said it was closed Saturday for a private event.

Heavily armed law enforcement was seen at the scene.

The Associated Press and Reuters contributed to this report.