The Latest on the Syrian conflict (all times local):

5:45 p.m.

Syrian activists say eight family members, including five children, have been killed in an airstrike apparently carried out by the U.S.-led coalition as they fled the Islamic State-held town of Tabqa.

The Britain-based Syrian Observatory for Human Rights says the family was fleeing in a car from fighting between U.S.-backed Syrian Kurdish forces and Islamic State militants on Monday.

It says the children were between six months and 15 years old.

The activist-run Raqqa is Being Slaughtered Silently also reported the airstrike, saying a family was killed.

The US.-backed Syrian Democratic Forces, which also include Arab fighters, have surrounded Tabqa, some 40 kilometers (25 miles) southwest of Raqqa, the de facto capital of the Islamic State group. They aim to expel the militants from Tabqa before attacking Raqqa.

The Observatory said the U.S.-backed fighters entered Tabqa on Monday but the town remains largely under IS control.


12:05 p.m.

Al-Qaida's leader has urged his followers and all militants in Syria to unite ranks and prepare for protracted jihad, or holy war.

Ayman al-Zawahri tells the jihadis to remain steadfast and change tactics to a guerrilla war. His remarks came in an audio message released on Monday by al-Qaida's media arm As-Sahab.

Al-Zawahri says an "international satanic alliance" will never accept Islam's rule in Syria. He says the war isn't an exclusively nationalist Syrian cause but a campaign by the entire Muslim nation that seeks to establish divine rule.

Al-Qaida's Syria branch — formerly the Nusra Front but now known as the Fatah al-Sham Front — has come under increasing attack from the U.S.-led coalition in recent months and some of its most senior leaders have been killed in airstrikes.