About eight people were injured Friday in India's tech capital when an improvised bomb went off inside a popular cafe, a state official said.

A "small improvised explosive device" blew up at a busy eatery in Bengaluru around mid-day causing panic, Chief Minister of Karnataka State Siddaramaiah, who goes by one name, wrote on social media platform X.

Bengaluru, known as "India's Silicon Valley", is home to many of the country's top information technology companies.

Siddaramaiah said preliminary investigations suggested the explosive was hidden in a bag left by someone who had breakfast at the cafe.

"Around eight people were injured in the incident," he said, promising "strict action against the culprits".

Local media put the number of injured at nine, including some members of the cafe's staff.

"The movements of the accused (suspected) are being tracked by the police," the Indian Express newspaper quoted the state's deputy chief minister D. K. Shivakumar as saying.

Police were also examining CCTV footage as part of their investigation, Siddaramaiah said.

"Whoever did this will be found out," he added.

Karnataka state is ruled by the opposition Congress party, which is often accused of being soft on terrorism by Prime Minister Narendra Modi's ruling Bharatiya Janata Party.