When Kadhum Abid Jabir came to Baghdad with his wife and granddaughter a week ago, he didn't know that he would go back to his home town alone to mourn their deaths. He lost both companions Thursday to a suicide bomb that killed more than 20 Iraqis and wounded dozens more.

"They killed my life and my future," Jabir, who lost an eye in the blast, cried in his hospital bed. All around him, other wounded people had relatives to wipe blood from their faces and talk them out of shock. But Jabir was alone, isolated in a corner. He gazed at the ground with an empty look. He didn't blink when the doctor worked on his wounds.

"How will I go back without them?" he whispered to himself. "What will I tell the family?"

The explosion ripped through al Nahdha bus station in the center of Baghdad when a suicide bomber, apparently wearing an explosive belt, jumped onto a bus filled with more than 40 people, police and witnesses said. The bus was bound for Nasiriyah, a city in the Shiite Muslim-dominated south, 200 miles from Baghdad.

The Sunni Muslim-led insurgency has frequently targeted Shiite civilians, as well as Iraqi security forces and other institutions of the Shiite-dominated government. As the country heads toward nationwide elections next Thursday, insurgent leaders have vowed to derail the balloting and target voters. Iraqi and U.S. officials have said they expect violence to escalate.

In the Shiite holy city of Najaf, a conference of southern political leaders recommended Thursday that nine Shiite-majority provinces forge a common security policy and form a regional security force. Abdul Hussein Abtan, deputy governor of Najaf province, said the conference sought to "provide protection to our population, and our cities and provinces, which are exposed to terrorist attacks."

Also in Najaf, Abdul Aziz Hakim, whose Supreme Council for the Islamic Revolution in Iraq is the leading party in Iraq's government and heads a Shiite slate in the coming election, renewed his vow to forge the nine Shiite provinces into a single federal region. In October, Iraqi voters approved a new constitution that would permit formation of such autonomous regions, much like that already established by ethnic Kurds in northern Iraq.

"Our region shall be formed at the desire and request of the people through a referendum as enshrined in the constitution," Hakim said at a news conference. "Our main challenge now is to establish a secure atmosphere in the center, the south and other parts of Iraq."

The bus bombing in Baghdad occurred at the peak business hour at a depot located on a street that is so busy it is almost impassable at any time of day. The bus station houses and is surrounded by fast-food restaurants and shops that sell cigarettes and soft drinks.

"I just heard a huge explosion," then saw a scene of carnage, Jabir said. After the blast, the bombed bus burned for more than 30 minutes.

Workers at nearby Kindi Hospital said the facility received 24 bodies from the scene and 28 wounded people.

"All the dead cannot be recognized. They are all burned," said Dhia Fuad, 31, a policeman guarding the hospital's gate. Fuad said that he had manned a checkpoint there for about three years and that "of all the dead and wounded from explosions I saw, this is the most horrible."

Fuad Abdul Wahab, 17, said he saw the owner of a nearby restaurant running in the street with his head aflame. The man died in the hospital.

Relatives of the victims waited in the hospital's corridors for news. A woman who gave her name as Um Ahmed came with her husband and daughter. "Where are my sons?" she shrieked. When she arrived at the emergency room, she was told that one of her sons was in the operating room and might have lost his eyes.

Other people stood by hospital beds, weeping and imploring unconscious relatives to speak. A father begged his son to say, "I am alive."

Special correspondent Saad Sarhan in Najaf contributed to this report.

An Iraqi soldier inspects the site of a blast that ripped apart a bus as it was about to depart for a Shiite Muslim city in the south.