Sources in Jenin told Aljazeera.net that earlier today two settlers were attacked near a settlement in the village of Sabah al-Khair, close to Jenin.
It is unclear who attacked the settlers and what kind of injuries they sustained during the incident.
Israeli occupation forces began to fire intensively in and around Jenin later this evening. Witnesses described seeing Apache helicopters above the city.
A house near Sabah al-Khair was hit by an Israeli tank, local people said the army were trying to demolish the house. The Israelis allege the house is being used as a ''weapons factory'' to assist resistance fighters in Jenin.
Aljazeera.net spoke to witnesses in Sabah al-Khair. One said: ''The tanks came in and there was a lot of shooting going on. The tank then slammed into the side of a building and the we heard Apache helicopters above in the air.''
There is a small international presence in Jenin city in the form of peace activists from the International Solidarity Movement (ISM). The movement is made up of volunteers from around the world who assist Palestinians in non-violent resistance against the occupation.
Aljazeera.net spoke to two ISM activists in Jenin, who described the mood in the city.
''People are used to hearing tanks and Apaches. There's always firing going on in and around Jenin,'' said one volunteer, who did not want to be named for fear of reprisals from the army.
''We are sick of hearing these machines of war, but we are grateful that there is no curfew in the city and that we can move around with a degree of freedom,'' added a Jenin resident.
The Israeli occupation army was unwilling to confirm the incident had taken place, saying that it was unable to comment on grounds of security.