Bombardment by the Syrian regime and its Russian ally killed 18 civilians including five children in northwest Syria Wednesday, a monitor said, in the latest violence to hit the opposition-run bastion. The Syrian regime and Russia have stepped up their deadly bombardment of Idlib province and adjacent areas in Aleppo and Hama provinces since late April. Among those killed Wednesday were 10 civilians including three children, all from the same family, hit by Russian airstrikes on a farm near the town of Khan Sheikhun in Idlib province, the Syrian Observatory for Human Rights said. Eight others including two children lost their lives in regime airstrikes and artillery fire in other parts of the bastion of some three million people, the Britain-based monitor said. The spike in violence since late April has killed around 720 civilians, according to the Observatory, which relies on sources inside Syria for its information. More than 330,000 people have fled violence in the area over the past three months, the United Nations says. On Monday, airstrikes killed at least 50 civilians in various parts of the bastion. Mark Cutts, UN deputy regional humanitarian coordinator for the Syria crisis, this week described a worsening "nightmare" unfolding in Idlib. He described Mondays aerial onslaught as "one of the deadliest attacks on civilian areas that we have seen since the upsurge in fighting". The Idlib region has since January been administered by Hayat Tahrir al-Sham, a group led by Syrias former Al-Qaeda affiliate. But other extremists and opposition factions are also present in the area. Despite the heavy bombardment, regime forces have been unable to make any significant advances. Militant groups have hit back hard, killing an average of more than a dozen regime fighters and allied militiamen per day in recent weeks. The fighting has killed more than 2,000 people and displaced hundreds of thousands. The struggling campaign also underscores the limits of Syrias and Russias airpower and inability to achieve a definitive victory in the countrys long-running civil war, now in its ninth year. Syrias war has killed more than 370,000 people and displaced millions since it started in 2011 with a brutal crackdown on anti-regime protests.