Officials with Metrolinx are working "as fast as we can" to make schedule changes to the Kitchener GO Transit line, a spokesperson for the agency says, after tweaks to train times led to dangerous overcrowding at Union Station earlier this week.

Riders took to social media on Monday and Tuesday with photos and videos of long lines and full platforms between 4:30 and 5 p.m. as passengers waited for the train servicing the Kitchener line. One Twitter user, @jezleo, reported that minutes before departure one afternoon, passengers were "pushing and shoving and getting crushed" trying to board a train.

"Why doesn't the head of Metrolinx and GO come down and see this is dangerous," @jezleo wrote. "Bring back the 4:50 express train to ease the burden for your clients!"

Another rider, Haider Inayat, "could barely keep from being shoved to the yellow line and on to the rails," earlier this week.

5 minutes before departure. People are pushing and shoving and getting crushed trying to get on this train before the doors closed. Why doesn't the head of Metrolinx and GO come down and see this is DANGEROUS. Bring back the 450 express train to ease the burden for YOUR CLIENTS! —@jezleo Constables on duty talking about shutting the staircases 15 mins before the train departs... walked 5 minutes on the platform and could barely keep from being shoved to the yellow line and on to the rails. Great show <a href="https://twitter.com/GOtransit?ref_src=twsrc%5Etfw">@GOtransit</a><br>And <a href="https://twitter.com/GOtransitKT?ref_src=twsrc%5Etfw">@GOtransitKT</a>, welldone<a href="https://t.co/M0TMf5ust7">https://t.co/M0TMf5ust7</a> —@HaiderInayat

Metrolinx spokesperson Anne Marie Aikins said Thursday changes to the schedule were prompted by the addition of a train on the line that will service Kitchener, Guelph, Acton, Georgetown and Mount Pleasant.

"We had to change some of the existing times of the express trains, change a few things here and there with the schedule," she told CBC Toronto in a telephone interview.

The revised schedule came into effect on Monday.

"We anticipated that it would cause some difficulties for some customers," Aikins said. "But I think we didn't anticipate just how much it would."

For one trip in particular, she said, there were "way more customers than we could handle."

Metrolinx staff were on the platform this week to observe the issue, she said, and work is already underway to make changes.

"We know that the schedule isn't working for people so we are working very, very hard and as fast as we can to put some fixes in place," she said.

She expects to be able to announce a fix in the next week or two, she added. In the meantime, extra transit safety officers have been deployed to improve crowd management and keep travellers safe.

Brampton Mayor Patrick Brown visited commuters Thursday morning after being "inundated with complaints about overcrowding, delays and the cancelled express train," he said on Twitter.

Visited <a href="https://twitter.com/hashtag/Brampton?src=hash&ref_src=twsrc%5Etfw">#Brampton</a> commuters this morning at the Go Train station to see first hand the problems with the recent <a href="https://twitter.com/GOtransit?ref_src=twsrc%5Etfw">@GOtransit</a> schedule changes. We have been inundated with complaints about overcrowding, delays and the cancelled express train. <a href="https://twitter.com/hashtag/brampoli?src=hash&ref_src=twsrc%5Etfw">#brampoli</a> <a href="https://t.co/TYuoYPpyop">pic.twitter.com/TYuoYPpyop</a> —@patrickbrownont

On Wednesday, Brown wrote a letter to Ontario Transportation Minister Jeff Yurek, asking that he "reconsider adding an express train that was cancelled and adding more coaches to meet the demand." That same day, Yurek issued a statement blaming the overcrowding on "expanded service" on the line, but said he is taking commuters' concerns "very seriously."

Yurek said he has "directed Metrolinx to look at all options to resolve" overcrowding, and noted the deployment of transit safety officers in the meantime.