If this was your first time at the Tecate Pa’l Norte festival and you weren’t familiar with the surprise stage concept, you probably freaked out when a tornado-like siren began ringing exactly at 7 p.m. It was no tornado. Instead, the sound alerted attendees that the first surprise artist of the night was about to start performing at the Sorpresa stage.

These artists are not previously announced on the lineup, and a total of two surprise acts perform per day. They are short sets — artists typically have around 10-15 minutes to sing. The first surprise artist on Friday (March 29) was the elusive reggaeton duo Angel y Khriz.

The pair started their set shortly after Belanova had wrapped on the main stage. The reggetatoneros started off with their massive 2005 hit “Ven Bailalo.” They quickly followed it with the equally infectious “Na De Na.” And then time was up. They thanked fans and left the stage.

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The second act to take the stage, at 8:52 p.m., was latest regional Mexican breakthrough artist Xavi — setting the perfect vibe for upcoming headliner Peso Pluma. The 19-year-old Mexican-American artist, who kicked off his Poco a Poco Tour in Mexico City on March 28, performed a total of five songs, including “La Víctima” and “Corazón de Piedra.”

The Pa’l Norte festival is taking place March 29-31 at the Parque Fundidora in Monterrey, Nuevo León, in Mexico. Headliners for this year’s edition include Peso Pluma, Blink-182, Maná, Fuerza Regida, Louis Tomlinson and Thirty Seconds to Mars. Kendrick Lamar was set to headline on Friday but canceled his performance because of “unseen circumstances due to logistical issues,” according to a statement by the festival organizers.

Below, see an updating list of all the surprise artists who performed at the Sorpresa stage.