Several workers of the Bharatiya Janata Party were injured in an explosion that took place while they were celebrating Prime Minister Narendra Modi’s birthday in Chennai on Thursday.

A party member was quoted telling NDTV that helium-filled balloons used during the celebrations triggered the explosion after being hit by fireworks. However, a senior police officer reportedly said that it was unclear whether the balloons were filled with helium or hydrogen. “We have registered a case of violating social distancing and prohibitory orders,” the police officer was quoted as saying.