A man and a woman have been arrested in connection with a bomb attack in Salamanca, Guanajuato, that killed two people at a birthday party last Sunday.

The owner and manager of a bar/restaurant were killed when a package with a balloon attached to it exploded seconds after they received it outside the establishment.

The Guanajuato Attorney General’s Office announced the arrest of Eduardo “N.” and Georgina “N.” – the alleged masterminds of the attack – on Thursday.

Attorney General Carlos Zamarripa said they were business partners of the bar’s owner and were owed money.

Their commercial arrangement turned sour due to a large debt, he said. “There was a partnership between them, we can’t say whether it was formal but what’s certain is they had a commercial relationship [that was formed] to open the restaurant, an amount in the millions [of pesos] was provided,” Zamarripa said.

Media reports initially linked the attack to non-compliance with extortion demands made by the Jalisco New Generation Cartel, but the arrest of the two business partners indicates that was not the case.

The homemade bomb was detonated remotely and injured five other people including the person who delivered it.

Zamarripa said authorities were able to track the suspects down after reviewing messages they sent to the courier’s cell phone. “Take [the package] to bar Barra 1604 and ask for the owner,” one message said.

With reports from El País