hello welcome to bbc news, i m mark lowen. we are coming to you live from southern israel. israel has promised to provide proof to back up its claim that hamas was using gaza s largest hospital as a command centre. hamas has repeatedly denied the allegations. president biden says the us has asked israel to be incredibly careful, as its military operation at al shifa hospital, which began yesterday, continues. the one thing that has been established is that hamas does have headquarters, weapons, material below this hospital and i suspect others. our correspondent lucy williamson has been with the idf at al shifa hospital where israel has promised to show proof of a hamas command centre at gaza s largest hospital. she spoke to us from jerusalem. israel is really coming under pressure to prove why it carried out the operation it is carrying out in gaza and driving into gaza last night it was clear the scale of the military operation there. parts of city looked as if it had been