Commuters are facing a difficult journey home as heavy snow falls in parts of Scotland.
A Met Office amber weather warning for snow and ice is in force for many areas until 22:00.
Heavy snow showers are affecting Strathclyde, Central, the Lothians, south west Scotland, Tayside and Fife.
Police Scotland earlier increased its travel warning from stage 2 to stage 3, meaning travellers are likely to experience significant delays.
A number of roads have been blocked by stranded vehicles including jack-knifed HGVs.
At 16:40, Traffic Scotland warned that the northbound carriageway of the M77 motorway was closed at Kingswell near Kilmarnock.
Supt Louise Blakelock said: “As we progress into this afternoon and evening, I would like to remind the public of the ongoing risk of disruption due to the forecast.
“If you travel on the road network in the warning area, you will be disrupted and you will face significant delays.
“With that in mind I would urge the public to think and plan ahead for their return journey home this afternoon.”
She added: “Please ensure you are checking the most up to date information from Traffic Scotland and the Met Office.”
Transport Minister Humza Yousaf has warned people to think carefully before setting off.
He said: “If you choose to travel, particularly in the evening peak period, you are likely to face significant delays and disruption.”
A number of schools were closed in South Lanarkshire, the Borders, Dumfries and Galloway, Fife and the Highlands.
School transport was also affected in some areas.
South Lanarkshire and North Lanarkshire councils closed all schools at lunchtime. Schools in Clackmannanshire also shut early.
NetworkRail Scotland said it had faced some challenges because of snow. It said teams were working hard to keep tracks free of snow so trains could run.
It said it was preparing to deal with more falls as they arrived in the course of Friday.
ScotRail said it was dealing with weather-related disruption on the West Highland Line at Crianlarich.
Most of Scotland is covered by a yellow Met Office warning for ice.
The Met Office said snow showers will become heavier and more frequent early on Friday and will continue on and off through the day.
Spells of more persistent, heavy snow are likely. There is expected to be a gradual improvement during the late evening.
A guide to travel warnings
Travel conditions are graded at four levels by police and transport officials depending on the severity of the weather.
- Stage 1: Normal operations – no severe weather.
- Stage 2: Travel with caution – police advise people that conditions for road travel may be hazardous.
- Stage 3: High risk of disruption for road journeys – police advise that there is a high risk of disruption for road journeys. Travellers are likely to experience significant delays.
- Stage 4: Avoid travelling on the roads – journeys should be avoided. Severe delays expected.
What the weather warning colours mean
- Yellow: Severe weather expected. Yellow means you should plan ahead thinking about possible travel delays, or the disruption of your day-to-day activities.
- Amber: Be prepared for disruption. There is an increased likelihood of bad weather affecting you, which could potentially disrupt your plans and possibly cause travel delays, road and rail closures, interruption to power and the potential risk to life and property.
- Red: Extreme weather is expected. Red means you should take action now to keep yourself and others safe from the impact of the weather. Widespread damage, travel and power disruption and risk to life is likely. You must avoid dangerous areas and follow the advice of the emergency services and local authorities.