NEW DELHI -- Loud blasts were heard in Indian-controlled Kashmir on Saturday evening, just three hours after India and Pakistan agreed to observe a ceasefire and end military actions, officials said.

The massive blasts were audible in Srinagar city, the summer capital of Indian-controlled Kashmir.

According to the region's Chief Minister Omar Abdullah, explosions were heard across Srinagar. "This is no ceasefire. The air defense units in the middle of Srinagar just opened up."

It was reported that in Akhnoor, Rajouri, and R S Pura sections, the two sides exchanged heavy shelling and artillery. The exchange of fire was also reported along the Line of Control (LoC) in Palanwalla section of Jammu.

Immediately after the blasts, a blackout was enforced.

Earlier in the day, Pakistan and India announced that they had agreed on a ceasefire.

The announcement came following four days of military strikes on each other.

On Wednesday, India launched airstrikes on Pakistani targets to avenge last month's killing of 26 people by gunmen in Pahalgam town, about 89 km east of Srinagar, the summer capital of Indian-controlled Kashmir.

India blamed Pakistan for being behind the incident, a charge denied by Pakistan.

The situation along the LoC dividing Kashmir had been tense as troops of India and Pakistan deployed on both sides of the ceasefire line were engaged in an exchange of fire and artillery.