A third blast in less than a week shook the area around the Sikh holy site of the Golden Temple in Amritsar, Indian police said Thursday.

No injuries were reported in what police described as a low-intensity blast at around midnight in the northern Indian city. The cause was not known.

"The area is totally sealed and a forensic team is working on it," police official Naunihal Singh said.

Police added that five people were arrested on Thursday, without giving further details.

The previous two blasts, one on Monday and the first last weekend, each left one person injured. Police have yet to reveal any cause for those explosions.

The Golden Temple in Punjab state -- a gleaming edifice in a large artificial pond -- is revered by Sikhs the world over.

But it has been the scene of violence in the past, most notably when Indian special forces stormed it in 1984 to remove Sikh militants.

In March, a manhunt was launched in Punjab to arrest a firebrand Sikh separatist that sparked protests and vandalism among the diaspora.

It was unclear if the latest blasts were linked.

Pressure for a separate Sikh homeland known as Khalistan sparked deadly violence in India in the 1980s and 1990s.