The Fourth of July was marred by shark attacks in Texas and Florida that injured three people, including one severely, as authorities warned swimmers to take “precautions” when entering the water, according to reports. Two people were bitten by a shark off South Padre Island off the coast of Texas on Thursday morning and two others “encountered” the predator but were not seriously injured, the Texas Parks and Wildlife Department said in a statement. The two injured in the attack, caught on video posted to social media, were transported to a hospital in Brownsville, and one of them was “flown o…