President Donald Trump on Monday called for “strong background checks” on gun purchasers, following a devastating weekend in the U.S. during which two mass shootings in less than a day left 29 people dead.

“We cannot let those killed in El Paso, Texas, and Dayton, Ohio, die in vain. Likewise for those so seriously wounded. We can never forget them, and those many who came before them. Republicans and Democrats must come together and get strong background checks, perhaps marrying this legislation with desperately needed immigration reform,” Trump said in a pair of tweets Monday morning.

“We must have something good, if not GREAT, come out of these two tragic events!” he added.

On Saturday, a gunman opened fire into a crowd at an El Paso, Texas, retail area that is popular among both local residents and shoppers from just across the border with Mexico.

Then early Sunday, a shooter attacked a crowd outside a popular bar in Dayton, Ohio, as patrons were enjoying a night out.

As a president, and as a presidential candidate, Trump has been an avid supporter of Second Amendment rights.