Story highlights Someone noticed a suspicious bag on the bus, authorities say

Passengers were evacuated "just in time," police spokesman says

The blast came as an expert dismantled the device

It seems to be a terrorist attack, prime minister's spokesman says

A bomb exploded on a public bus in Israel on Sunday, moments after passengers evacuated.

Someone spotted a suspicious bag and reported it to the driver, police spokesman Micky Rosenfeld said.

"The passengers were immediately taken off the bus," he said, and made it out safely "just in time."

The bomb detonated while an expert was examining the bag. He was shaken, Rosenfeld said, but not injured seriously.

A photo Rosenfeld posted on Twitter showed windows blown out on the bus and shattered glass on the ground.

"It seems that the bomb that exploded on a public bus near Tel Aviv was indeed a terrorist attack," Ofir Gendelman, spokesman for Israeli Prime Minister Benjamin Netanyahu, said on Twitter.

Police are searching the area for suspects, Rosenfeld said.

According to the Israeli Foreign Ministry, the last bus bombing in the country was in November 2012 and wounded 21 people.