Three people died, and 21 others suffered injuries after a bomb exploded outside a restaurant in central Moscow on Saturday. Russian authorities have started an investigation into the deadly incident.

According to Russia’s National Anti-Terrorism Committee, an unidentified woman walked toward the entrance of the Balzi Rossi restaurant carrying what investigators believe was a homemade bomb. However, a security guard stopped her before she could enter. Moments later, the device exploded.

The explosion killed the woman, the security guard, and a restaurant customer. Investigators have not released the woman’s identity. They also have not explained what may have motivated her. In addition, they are still trying to determine whether she intended to trigger the explosion.

The blast happened at about 8:10 p.m. local time near the restaurant’s outdoor terrace on Kudrinskaya Square. Soon after the explosion, police officers, firefighters, and emergency crews rushed to the scene. They secured the area and began gathering evidence.

At the time, the restaurant was hosting a private event and was closed to the public. So far, officials have not said whether the event was the intended target. They continue to interview witnesses and examine evidence from the scene.

The Balzi Rossi restaurant sits at the base of the Kudrinskaya Square Building. The tower is one of Moscow’s famous “Seven Sisters” skyscrapers. These buildings date back to the 1950s and remain among the city’s best-known landmarks.

Meanwhile, investigators continue to examine the explosive device and search for clues. They also want to find out whether anyone helped plan or support the attack. So far, no group has claimed responsibility for the explosion.

After the blast, Chef Carmine Alfieri thanked people for their support. He said all restaurant staff were safe. He also said the restaurant and kitchen remained undamaged. According to Alfieri, the explosion happened near the entrance.

Authorities have not announced any arrests. Instead, investigators continue to gather evidence and question witnesses. They expect to release more information as the investigation moves forward.