Two leaders of the Islamic Jihad militant group have been detained for questioning by Palestinian Authority in Jenin on Wednesday.
It was not clear whether the arrest had anything to do with the deadly bombing that struck Jerusalem on Wednesday.
No group claimed responsibility for planting the bomb, which exploded near a crowded bus stop and left one woman dead and dozens wounded.
Prime Minister Benjamin Netanyahu warned militant groups in the Gaza Strip on Wednesday that Israel would act decisively to defend itself.
He threatened a lengthy "exchange of blows" with Palestinian militants, though officials from both sides have said they want to prevent a repeat of Israel's 2009 three-week war on the coastal enclave.
Deputy Defense Minister Matan Vilnai told Israel Radio following the bombing that: "The responsibility lies entirely on Hamas... we know how to act and have proven this in the past, we will strike proportionally when needed."
Israel Police do not believe that the bombing in Jerusalem was connected to the cross-border escalation between Israel and Gaza over recent days.
The Hamas rulers of the Gaza Strip say that the rockets emanating from the territory into Israel in the past week have been in response to Israeli air strikes. Five Palestinian militants and four civilians, three of them children, were killed by Israeli fire in the Gaza Strip on Tuesday.
Despite the escalation, Hamas does not seem to want large-scale clashes yet.
Hamas Prime Minister Ismail Haniyeh's office said Wednesday that the Gaza leader had phoned the secretary general of Islamic Jihad, Abdallah Ramadan Salah, in Damascus. Pundits in Gaza said Haniyeh asked Salah to stop the escalation, for which Islamic Jihad is mainly responsible.
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