West-side Spring Valley residents reported a power outage that started around 8 p.m. that also affected the Seatonville and Echo Bluff area.
Kemp Smith reported power went out right at 8 p.m., and a check of the Ameren Illinois outage map confirmed the outage started at 7:59 p.m.
"The entire town is out," said Todd Bogatitus, Spring Valley's fire chief.
He said the fire department had not been paged out as of 8:45 p.m., and when he took a drive around the city, he did not see anything that appeared to be the cause.
Ameren Illinois reported more than 2,600 customers without power in Spring Valley, Webster Park, Seatonville and the Echo Bluff area.
By 9:50 p.m., all but 292 customers had their power restored.
An initial report from Ameren had estimated electricity restoration time at 10:25 p.m.
Ameren was still assessing the cause as of 9:50 p.m.