"Morning trains for tomorrow (41, 43, 51, 61, 50, 60) will be replaced by bus and we will be announcing when there will be line clearance," the company tweeted on Thursday afternoon.
Via said that about 3,600 passengers were affected on Thursday by the derailment.
Later in the day, spokeswoman Mylene Belanger said the company had secured buses for the rest of the day to transport passengers.
"We don't expect line clearance by the last departure, which is scheduled for 7 p.m. tonight," Belanger said.
She said Via hadn't received any confirmation from CN to resume service.
CN said on Twitter late Thursday afternoon that crews were clearing derailed cars so the damaged rail line could be repaired and it hoped to have one line open late Thursday or early Friday.
CN said it was investigating the incident along with the Transportation Safety Board of Canada.
Lindsay Fedchyshyn, a CN spokeswoman, earlier said no one was injured.
Twenty-five cars on a 68-car eastbound freight train derailed, CN said.
The train included two loaded automobile carriers and had five cars carrying carbon powder and 13 unloaded fuel tank cars, she said.
The site was being assessed by local emergency crews for any possible leaks, Fedchyshyn said.
Jacques Gagnon, another Via Rail spokesman, said it can be difficult to find buses to transport passengers during the summer peak vacation season when charter buses are in high demand.
But the company managed to secure enough buses to maintain service until the cleanup is done, he said, calling the situation "a logistic challenge."
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