Ercis, Turkey (CNN) -- Witnesses to Turkey's most powerful earthquake in more than a decade described the devastation Monday as rescue teams picked through the rubble desperately searching for survivors.
The towns of Van and Ercis appeared to bear the brunt of the violent tremor Sunday, when hundreds of people were killed or injured as buildings collapsed around them.
In Ercis, Orhan Demir stood watching rescue workers pick away at the rubble of a six-storey apartment building. His brother and his brother's wife were both inside when the 7.2-magnitude quake hit.
Neighbors fear there are as many as 60 people trapped inside. Demir said he thought the quake was a bomb it had been so loud.
Turkish Prime Minister Recep Tayep Erdogan visited this particular site late on Sunday. Demir said he'd told him the municipality shouldn't have given out building permits for multi-storey buildings like this in an earthquake zone.
A civil engineer also working at the site told CNN he imagined buildings like these might have been constructed before regulations were tightened in the aftermath of the Izmit earthquake in 1999.
More than 17,000 people lost their lives and at least 200,000 were left homeless when the 7.6-magnitude quake shook the region in northwestern Turkey. Most victims had been buried as buildings were flattened.
Meanwhile, another Ercis resident, Ramazan Palas, said he felt at least 18 aftershocks.
But he said the devastation "could have been even worse if it hadn't been a Sunday, with people out, schools out."
Filiz Isler was sitting on her balcony in Van when the quake struck.
She said she'd thought it was thunder but then "when I tried to move it was as though someone had a plastic sheet beneath my feet and was pulling it from under me."
The buildings were collapsing "like a house of cards," she added.
She was four years old when another major earthquake struck Van in 1976, though she doesn't remember there being the same damage, perhaps because the buildings were not multi-storey back then.