Two of the injuries in the attack, which took place shortly before 3 p.m., were considered serious, according to news reports citing Magen David Adom, Israel's version of the Red Cross. One of the injured went straight to surgery at Hadassah Hospital; five others are reported in moderate condition, injured by shrapnel packed into the two-to-four pound bomb.
Prime Minister Benjamin Netanyahu said following the attack that he would delay a planned trip to Moscow.
Police say the bomb was left in a bag either in a telephone booth next to a busy bus stop, or in the bus stop itself, along a main artery in central Jerusalem, near the International Convention Center and about a block from the city's central bus terminal. The blast blew out the windows of two buses picking up passengers.
The entrance to the city of Jerusalem was closed following the explosion.
Jerusalem Mayor Nir Barkat called on citizens to return to their normal lives, so that the terrorists could not score a victory in the attack, The Jerusalem Post reported. He also asked Jerusalem residents to keep their eyes open in order to prevent future attacks. Barkat called the explosion a "cowardly terrorist attack."
A marathon through the streets of Jerusalem is scheduled for Friday. Barkat told reporters he still planned to participate in the run.
Jerusalem during the second Palestinian intafada was the site of dozens of attacks that targeted buses.
Meanwhile, Deputy Prime Minister Silvan Shalom threatened to launch a new operation against Gaza in the wake of increased shelling on Israel's South.
"The period of restraint is over; we must do everything we can to strike out against those who wish to hurt the innocent," said Shalom on a visit to a site in Beersheba struck by two long-range Grad rockets on Wednesday. "I hope it won't come to another Operation Cast Lead, but if there is no other choice we will launch another operation."
Shalom, of the Likud Party, grew up in the Beersheba residential neighborhood hit by the rockets, which left one man wounded. The attack followed a Grad rocket attack Tuesday on the port city of Ashdod; that rocket landed near the center of the city of 200,000. Ashdod schools were closed Wednesday following the attack.
At least seven mortars and one other rocket were fired into southern Israel on Wednesday morning. Israel's Home Front Command called on Israelis living in the country's south to go about their daily routine, despite the increasing rocket fire.
Earlier Wednesday, Israel's Air Force said it bombed the rocket launcher from which the rocket was fired into Ashdod.
Meanwhile, an 8-year-old Gaza boy injured in an Israeli attack was taken to an Israeli hospital Wednesday for treatment. The transfer of the boy to Israel was coordinated with the Palestinians.
J Street President Jeremy Ben-Ami and Board Chair Davidi Gilo, currently in Jerusalem for a Knesset debate, condemned the bombing,and the increase of rocket attacks on the south, in a statement.
"We support the state of Israel in taking the steps necessary to respond to today’s attacks, to protect all its citizens, and to bring those who perpetrated today’s attack to justice," the statement continued.