Thousands of Belarusians, including the authoritarian president, were gathered for an all-night holiday concert under a soaring war memorial early Friday, when a bomb blast tore into the crowd, wounding more than 50 people, health officials said.

The blast was unusual in the tightly controlled former Soviet republic, where President Alexander Lukashenko harshly suppresses dissent and public violence is rare. Officials blamed unspecified "hooligans" for the bombing. It was not clear if the attack was an attempt to assassinate Lukashenko, and there were no reported claims of responsibility.

He was not wounded in the blast, which hit about 12:30 a.m. at the Independence Day concert at the Hero City memorial in central Minsk that commemorates the city's World War II suffering.

Police later found an unexploded homemade bomb in the area, also packed with hardware, Interior Minister Vladimir Naumov said.

"It was an action by hooligans," said Minsk police department spokesman Alexander Lastovsky.

He said more than 20 people were hospitalized, but the Health Ministry put that number at more than 50.

Dmitry Kudyakov, a 32-year old engineer at the concert, said he felt a strong shock wave and saw smoke.

"People started crying," he said. "Some fell on me and there was a lot of blood."

Viktor Sirenko, chief doctor of the city's Emergency Hospital, said three people were in grave condition. "We are struggling to save their lives," he said.

Viktor Gurko, chief doctor of the city Hospital No. 6, displayed nuts and bolts that doctors recovered from the victims' bodies.

Most of those wounded were people in their 20s, but two children aged 5 and 6, and several elderly people, also were among the victims.

In 2005, two bombs went off in the city of Vitebsk, wounding around 50 people; one was at a bus stop and the other at an outdoor cafe.

Lukashenko has provoked Western condemnation and sanctions for his crackdown on dissent. Most U.S. Embassy employees have left Belarus in recent months amid rising tensions.

Lukashenko, who has ruled Belarus since 1994, is an open admirer of the Soviet Union.

The Independence Day holiday being marked at the concert commemorates the day in 1944 when the Soviet army drove Nazi forces out of Minsk. Prior to Lukashenko taking power, Belarus had celebrated Independence Day on July 27 to mark its 1990 declaration of sovereignty from the Soviet Union.