Aleppo battle ends after four years...or not. Alas.

A deal to evacuate rebel fighters and civilians from eastern Aleppo appears to have stalled, with heavy shelling reported in the Syrian city.

A ceasefire was declared in Aleppo on Tuesday and buses brought in to ferry people out of the devastated enclave.

But fighting resumed on Wednesday. Syrian activists also say air strikes over rebel-held territory have resumed.

Thousands of civilians and fighters have already been evacuated from the rebel-held enclave: Some 3,000 civilians were evacuated in the first few convoys, along with more than 40 wounded people, the International Committee of the Red Cross said Thursday.

The aid group anticipated it would take days to fully evacuate east Aleppo.

But on Friday, efforts were halted, NPR's Alison Meuse reports.

"The World Health Organization Syria rep Elizabeth Hoff says her staff were told to leave the evacuation area south of the city 'without explanation.' Hoff is in Aleppo and was addressing reporters at a new conference in Geneva," Alison says.

At one point on Friday, a witness to the evacuations told Reuters that a convoy had "ground to a halt" on the road out of eastern Aleppo, with people packed onto flatbed trucks exposed to the elements.

The weather in Aleppo this morning hovered around freezing, according to reporter Louisa Loveluck.

Reuters reports that there are "recriminations on all sides," with various explanations for why evacuations have stopped