Lebanon claims 54 medics killed in Israeli invasion.
Total casualties exceed 1,400 according to Lebanese sources.
Human rights groups allege targeting of first responders.
Israel denies accusations of targeting medical personnel.
Briefing: In Lebanon, more than 50 medics have been killed by Israel. Some say they're targeted
Strategic angle: Lebanon reports at least 54 health workers among over 1,400 fatalities due to Israeli actions, with claims of targeted attacks on first responders.