Rashi: They rushed to go out to greet him.

Radak #1: They moved and gathered to go out to greet him. The same applies to "Yecherdu ch'Tzipor mi'Mitzrayim", "va'Yecherdu Vanim mi'Yam" (Hoshe'a 11:11, 10). Also Yonason translated 'gathering.'

Radak #2: It is from the root Charadah. They were afraid - why did Shmuel come? Did someone do a great sin, that Shmuel needed to come [to rebuke him]? Refer to 16:5:1:1.

Malbim: They saw that he has a calf. They feared lest a murdered body was found near Beis Lechem, and he came to behead the calf in the valley. Ralbag holds that this is why Hashem said to take a calf! This is why specifically the elders of the city were afraid; the Mitzvah is incumbent on them - "v'Yatz'u Zekenecha

Radak: The greatest of the city greeted him Perhaps it was Yishai.