The bomber was spotted wearing a long black coat on a hot day
An Israeli security guard has been killed and at least 10 people injured in a suicide bombing in the town of Kfar Saba, Israeli police say.
The attack happened shortly after 0700 local time (0400GMT) on Thursday as the morning rush hour began.
Israeli police say the bomber, who also died, detonated his explosives when he was challenged by security guards at the entrance to the city's new train station.
In a separate incident, two Palestinian men were shot dead by Israeli troops in a village near the West Bank town of Ramallah.
The two incidents came shortly after the end of a stand-off between Palestinian leader Yasser Arafat and his designated prime minister, Mahmoud Abbas, potentially opening the way for a new stage in efforts to bring peace between Israelis and Palestinians.
A man claiming to be from the al-Aqsa Martyrs Brigades, an offshoot of Mr Arafat's Fatah group, has called news agencies to say it was responsible for the Kfar Saba attack.
He named the bomber as 18-year-old Ahmed Khatib from the northern West Bank town of Nablus.
However, official al-Aqsa spokesman Abu Mujahed said his group had nothing to do with the bombing and blamed a splinter group.
There has been no official claim of responsibility.
The BBC's James Reynolds was told at the scene that the station guards had become suspicious because the man was wearing a thick black coat, despite the high temperatures.
Regional police chief Amichai Shai praised the guards.
"If he had managed to get inside the station, we would have seen many more casualties," the Jerusalem Post newspaper quoted Mr Shai as saying.
Reports from the scene say the entrance to the station was left a twisted mass of metal, broken glass and body parts.
A BBC correspondent in Jerusalem, Simon Wilson, says Israeli security forces were on high alert as the week-long Jewish holiday of Passover came to an end.
In the Ramallah incident, Israeli troops reportedly opened fire after youths pelted them with rocks.
The dead were named as Osama Hamdulla, 24, and Fakr Ezzet, 18. Two others were wounded.
The army said soldiers opened fire as they felt their lives were in danger.
Prime Minister Ariel Sharon's office was quick to condemn the suicide attack.
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"The Kfar Saba bombing was a vicious attack against Israeli civilians and another attempt to instil fear in the heart of Israelis," said David Baker, an official in Mr Sharon's office.
It has been nearly a month since the last suicide bombing - an attack in the coastal town of Netanya, that wounded about 30 people.
Thursday's explosion came only hours after Mr Arafat backed down in a confrontation with his new prime minister over who would head security services in a new cabinet.
The prime minister-designate, Mahmoud Abbas, favoured Mohammed Dahlan, seen as a moderate pragmatist - and got his way.
The militant group Hamas has condemned Mr Dahlan, accusing him of betraying his people.
The agreement on the cabinet will usher in a new phase in the drive for a peace deal between the Israelis and the Palestinians.
The United States says that, once the cabinet is approved by the Palestinian Legislative Council, it will publish the so-called "roadmap" to peace it drafted late last year with the European Union, Russia and the United Nations.