Four senators working on an immigration bill got a first-hand look at the challenges – and, perhaps, the successes – of securing the nation’s border with Mexico on Wednesday.

During a tour of border control measures in Nogales, Ariz., the foursome saw a woman successfully scale an 18-foot fence, according to an account provided by Sen. John McCain (R-Ariz.) on Twitter. McCain attached a photo of himself and Sen. Charles Schumer (D-N.Y.) on the tour, though the woman was not visible in the shot.