MANDALAY, Burma – Police are yet to determine who was behind the blast Sunday (July 21st) that wounded five people attending a sermon by the ultranationalist Burmese monk U Wirathu, The Irrawaddy reported.

Wirathu almost immediately blamed Islamist extremist for the blast, which witnesses said was set off by a crude handmade bomb. However, Mandalay divisional police superintendent Soe Nyein said such accusations were premature.

"It is too early to say that the perpetrators were Islamic terrorists," he told The Irrawaddy, adding that they are still investigating the cause of the blast.

Given the varying eyewitness accounts, police say they are still uncertain about how the attack was carried out.

"In the area of the crowd, something fell from above with sparks and later I heard a thundering sound and saw a car was hit and its tires were on fire, The Irrawaddy quoted Ye Htun, who attended the sermon, as saying. "Many people tried to extinguish the fire by throwing sand (on the flames)."

A Mandalay police officer, however, said the bomb was thrown into the venue but landed underneath a parked vehicle. The resulting injuries were caused by shrapnel as the bomb included pieces of iron, nails and wires.