Shafaq News/ A thundering explosion rocked London’s Trafalgar Square Saturday morning, sending hundreds of terrified visitors running shortly after police evacuated a section of the popular tourist spot on Day 3 of the Queen’s Platinum Jubilee celebration.

The evacuation followed a 9:20 a.m. call to the Metropolitan Police about a suspicious vehicle in the square, The Sun reported.

The police tweeted about an hour later that the vehicle “was investigated and after police took action, we have no further concern.”

“This was not terrorism related,” the tweet said.

A concert was scheduled outside Buckingham Palace, a short distance away, later Saturday.

In a separate tweet, police said the “the incident has now been concluded and the square will reopen in due course.”

But the source of the explosion that panicked the crowd was not immediately explained.

Global News Reporter Crystal Goomnsingh, who was in the area at the time, tweeted that “Met Police conducted a controlled explosion after a suspicious was vehicle located.”

“Please don’t panic that you heard a bang,” an officer on site said, she reported in another tweet.

A woman tweeted that her hotel on the square was also evacuated because of “suspicious car unattended outside.” A second tweet showed a police van behind a cordoned off area.

Witnesses on the scene said the explosion panicked the crowds.

Tourist Sarah Churchill, 38, who was in the square with her 11-year-old son Noah, told the Mirror: “I was in the square when the bomb went off.”

She continued: “There were lots of police, were were just about to walk through the square when we got to corner we saw it was cordoned off.

“We were speaking to a policeman when the bomb went off without any warning,” she said, “It was intensely loud and intensely quick.”

The boy was terrified, she added. “My son is crying, he’s absolutely beside himself,” she said. “I had nothing to tell him. I didn’t know if it was a terrorist, or if they’d be more bombs.”

Another person told the paper that a panicked crowd of 150 people ran as the loud bang shook the square in the center of the city.

“He had told us it was a suspicious package, I don’t know if was a controlled explosion, but no one told us it was about to go off,” the shaken up woman said. “The policeman looked shocked.”