A series of blasts occurred in six places across the city on Friday afternoon.

A woman passing by was killed on the spot at Nayandahalli. Several persons were injured and many have been admitted to St John's Hospital.

Unconfirmed reports said three persons were killed.

Explosives hidden in drains exploded first near Madiwala checkpost at around 1.30 pm.

The second blast occurred near a bus-stop in Nayandahalli, followed by Adugodi and Longford Road near Richmond Circle.

The police rushed to the spots and cordoned off the areas.

An eyewitness at Nayandahalli said, "We were watching television, when we heard a big explosion. Initially we thought it was a transformer blast.

"We came out and saw smoke all around. Slabs covering a drain were ripped into pieces."

Police suspect they are terror attacks but did not rule out the fact that they could be an act of mischief to destabilise the government.

City Police Commissioner SM Bidri requested residents to "keep calm as the perpetrators were trying to disturb the peace and harmony".

Last Friday, the city was tense after the desecration of places of worship in JC Nagar and near Hebbal flyover.