The Mysterious Elevator Ride

One day, a friend returning to the dormitory after work pressed the elevator button on the first floor. He needed to go to the sixth floor.

Very luckily, the elevator arrived immediately. He stepped inside, and there was no one else in it. As he entered, the elevator doors closed right away.

Going up... ascending...

When he reached the fourth floor, the elevator suddenly opened. Two people were outside, trying to peek in, seemingly wanting to get in, but for some reason, they hesitated and decided not to enter.

The elevator doors closed again, and just as they were about to shut, my friend distinctly heard them saying, "Why are there so many people in there!"