Israeli fire has killed a Palestinian at the Gaza border and another has died of wounds suffered several days ago, officials say.
The latest deaths on Thursday brings to 19 the number of Palestinian dead from a week of protests.
The Israeli military said one of its aircraft targeted an armed militant, identified as 23-year-old Mojahid al-Khodari, near the security fence along the Gaza Strip.
Tens of thousands of Palestinians are holding a six-week-long protest along the fenced border of the Israeli-blockaded Gaza Strip, an enclave of two million ruled by the militant Hamas Islamist group.
The demonstrators are pressing for a right of return for refugees and their descendants to what is now Israel.
The latest deaths are likely to add to international concerns over the violence, which human rights groups have said involved live fire against demonstrators posing no immediate threat to life.
Sixteen Palestinians died after being shot by Israeli troops on the first day of the demonstrations, Palestinian medical officials said, and another was killed on Tuesday.
A 33-year-old man, hit by Israeli fire a few days ago near one of the tent cities, died on Thursday, the officials said.
Israel says it is doing what is necessary to defend its border and on Thursday chief military spokesman Brigadier-General Ronen Manelis warned they might attack deeper inside Gaza if the demonstrations did not stop.
"We have information that tomorrow (Friday), under a smoke screen and civilian cover, Hamas intends to carry out terrorist attacks against our civilians and troops, and cross the fence," he said.
Protesters on Thursday were bringing more tents and thousands of tyres to burn, in what has become known as "The Friday of Tyres".
They say they intend to use mirrors and laser pointers to distract Israeli sharpshooters.
Visiting the frontier this week, Israeli Defence Minister Avigdor Lieberman warned protesters that "every person who comes close to the fence is endangering their lives".