An explosion ripped apart a rush-hour commuter bus in a West Jerusalem neighborhood this morning, killing at least 10 people and wounding dozens, and the death toll was expected to climb, according to Israeli media reports.

The blast occurred at about 7:15 a.m. when a suicide bomber boarded the Egged No. 20 , which was crowded with morning rush-hour commuters, according to initial media accounts.

The bus was near a bus stop on Mexico Street, a residential thoroughfare, that cuts through Kiryat Menachem, a lower middle-class area of the city, when the explosion tore through the green bus, charring its interior, buckling its roof and spraying glass and debris across the street.

The explosion was the first in Jerusalem in four months and comes at the start of an Israeli election campaign for prime minister in which security is one of the most divisive topics.

It also came as Israeli military forces renewed crackdowns, curfews and sieges on most of the largest cities of the West Bank.

The bus was making its last stop in the residential neighborhood before it was scheduled to head downtown with a load of morning rush-hour commuters that likely included school children as well as workers.

Rescue workers lined stretchers along the street next to the bus as passersby made frantic cell phone attempts to call families and friends.

Many of the wounded were taken to Hadassah Ein Karem Medical Center, about a mile away from the blast site. Many passersby brought wounded and injured people to the hospital in their cars. Other victims were rushed to Sharei Tzedek Hospital.

Although fewer suicide bombings and other attacks have occurred inside Israel in recent months in comparison with the relentless spate of incidents this spring, assaults have continued despite the Israeli military's chokehold on the West Bank and Gaza Strip.

Based on the military's reaction to other recent attacks, the bombing today was likely to prompt further retaliatory military responses.

The most recent attack occurred Nov. 10, when a gunman sneaked into the Kibbutz Metzner in northern Israel and killed five people, including a mother and her two sons in their beds.

Two people died in a home-electronics store in a mall north of Tel Aviv on Nov. 4 in the most recent bombing attack and 14 people were killed on Oct. 20 when an attacker drove a car bomb into a bus near the Karkur Junction in northern Israel.