Two people were killed in the first result of a violent explosion that rocked the center of the Spanish capital, Madrid, today, Wednesday, and Madrid Mayor Jose Luis Martinez Almeida said that preliminary information indicates a possible gas leak.

Almeida told reporters that "two people were killed in an explosion that caused a partial collapse of a building in central Madrid and caused a fire inside."

He said, "Preliminary information indicates a gas leak that may have caused the explosion."

Activists on social media in the country posted videos that they said were of the site of the explosion.