пройдя через ворота, они оказались

пройдя через ворота, они оказались на платформе и через несколько уже сидели на своих местах

Результаты (английский) 2:

Go through the gate, they were on the platform, and a few were sitting in their places

Результаты (английский) 3:

after passing through the gate, they were on the platform and in a few already sitting in their seats