(CNN) -- ISIS intensified its attack on the city of Kobani as militants took a strategic hill Sunday evening and entered the southeastern edge of the city, a fighter and a media activist inside the city tell CNN.
The sources, who both requested their names be withheld for security reasons, said street-to-street fighting has started in Kobani.
ISIS has been trying to seize Kobani, an enclave for Kurds on the Syrian-Turkish border, for almost three weeks. The city is significant because ISIS wants to claim a swath of land running from its self-declared capital of Raqqa, Syria, on the Euphrates River to the Turkish border, more than 60 miles away.
ISIS fighters overpowered Kurdish forces to take the top and the eastern side of Meshta Nour, the strategic hill overlooking Kobani, the sources said.
A civilian source inside Kobani said there have been heavy clashes on all fronts around Kobani and that ISIS forces had been moved back from a small corner of the city they'd held for two days.
The Kurdish People's Protection Unit, or YPG, said in a statement that 86 "terrorists" were killed during a 24-hour period and 17 YPG members died.
On Sunday, smoke billowed over Kobani as ISIS sent bombs into the middle of town.
Battle for city on Turkish-Syrian border
Kobani is now tightly surrounded in a crescent from the Aleppo road on the southwestern outskirts of the city all the way to the eastern edge of Kobani, near the Turkish border, the fighter and media activist said.
ISIS is making inroads despite airstrikes by U.S. and allied forces, including Sunday's strikes on the eastern outskirts of the city.
The YPG destroyed an ISIS tank in the east of Kobani near Kane Kordan, a large mound on the eastern of the city, the civilian source said.
ISIS fighters are now about about one kilometer south on the Aleppo road, the civilian source said.
Turkish security force throw teargas
Conflict occurred outside Kobani when Turkish security forces fired tear gas canisters at Kurds gathered near the border to watch the fighting from afar, CNN's Phil Black reported.
Black said the security forces fired the tear gas when the crowds became restive or moved too close to the border. At least three canisters struck a CNN van, he said. Nobody was badly hurt and the crowds dispersed.
Pakistani Talilban supports ISIS
ISIS picked up support when Pakistani Taliban spokesperson Shahidullah Shahid issued a statement backing ISIS.
"The Muslims of the world look to you with great expectation and in this difficult time we your mujahidin brothers are with you and will provide you with fighters and help," the statement said.
Meanwhile, U.S. and allied military forces conducted three airstrikes against ISIS in Syria and six airstrikes in Iraq on Saturday and Sunday, U.S. Central Command reported.
In Syria, one strike northwest of Al Mayadin destroyed an ISIS bulldozer, two tanks and another vehicle, the military said. Two strikes northwest of Ar Raqqah hit a large ISIS unit and destroyed six firing positions.
In Iraq, four strikes northeast of Fallujah struck two mortar teams, a large ISIS unit and two small ISIS units, the military said. Three ISIS Humvees were destroyed with strikes near Hit and Sinjar.
Australians complete first air mission
Australia has completed its first air combat mission over Iraq, the government announced Sunday in a press release.
Two Royal Australian Air Force F/A-18F Super Hornet aircraft conducted an air interdiction and close air support mission over northern Iraq and were on-call to attack targets if needed, the release said.
The aircraft did not use their munitions and returned to base to disarm, the release said.
CNN's Ingrid Formanek in the Mideast and Yousif Basil in Atlanta contributed to this report.