Airstrikes stopped in the Idlib region on Friday (August 2nd) after the Syrian regime announced it had agreed to a truce, AFP reported.
The regime on Thursday agreed to a ceasefire in the Idlib region, largely controlled by Tahrir al-Sham, where regime and Russian airstrikes and shelling have killed hundreds of people since April, many of them civilians.
The truce went into effect Thursday evening, conditional on the implementation of a Turkish-Russian deal to enforce a buffer zone encircling the region.
"A cautious calm has reigned since just before midnight," said Syrian Observatory for Human Rights head Rami Abdel Rahman.
He said Syrian and Russian aircraft were no longer seen flying over Idlib while "fighting on the ground had also ceased on all fronts in the past few hours".
An early warning system known as Sentry registered the last air raids on Khan Sheikhun just two minutes before the truce took effect at midnight.
The Sentry programme uses human observers and a network of sensors to compute a predicted impact location when Syrian or allied warplanes take off.
The resulting estimate can trigger air raid sirens near the target zone and send warnings to mobile phone applications, giving residents more time to take cover.
UN Secretary-General Antonio Guterres on Thursday expressed hope that the truce would hold, and announced the UN will investigate several attacks on UN-supported facilities and other civilian sites in north-west Syria.
"The investigation will cover destruction of, or damage to facilities on the deconfliction list and UN-supported facilities in the area," a spokesman for Guterres said in a statement announcing the inquiry.
"The Secretary-General urges all parties concerned to co-operate with the board once it has been established," he added.