Smoke from tear gas cannisters is filling the air in several Egyptian cities for a sixth day as army soldiers clash with protesters calling for the country's miltary rulers to step down immediately.

The latest clashes erupted early Thursday east of Cairo, in Ismailia, a city along Egypt's Suez Canal. Some protesters tried to kick away tear gas canisters and others fled while the sound of steady gunshots rang out. Protesters also hurled Molotov cocktails at troops who moved through the streets in armored vehicles and tanks.

The clashes are just the latest in an ongoing standoff between the demonstrators and the country's ruling military council, which has made some concessions that have been rejected by the protesters.

More violence also flared in Cairo, where many protesters are refusing to abandon the iconic Tahrir Square. Ambulances rushed through the streets of the Egyptian capital late Wednesday, and some protesters accused the military of more unprovoked violence.

In the coastal city of Alexandria late Wednesday, protesters set up barricades and hurled stones at police. Others held hands in front of military buildings and chanted “freedom.”

U.N. High Commissioner for Human Rights Navi Pillay on Wednesday urged Egyptian authorities to end what she called “clearly excessive force against protesters” called images of the brutal beatings of subdued protesters “deeply shocking.”

At least 35 people have been killed during the past six days in clashes between security forces and protesters in Cairo and other main cities.

Field Marshal Hussein Tantawi, the head of the Supreme Council of the Armed Forces, has pledged to speed the transition to civilian rule with presidential elections before July 2012.

Parliamentary elections are set to begin on Monday and Tantawi pledged the polls would go forward as planned. But many opposition leaders believe that to be increasingly doubtful.

Meanwhile, Egyptian authorities said Wednesday three American students arrested during protests in Cairo earlier this week are being questioned by local police in the presence of a lawyer and a U.S. embassy official.

Egyptian media report that the three, all students at American University in Cairo, were detained along with other protesters while throwing petrol bombs at police.

No formal charges have been brought against the students, who insisted they did nothing wrong.